Volume Forty
ICs help implement a trim-free VCO (Part 2)
Maxim leads the way in ESD protection
Data Converters
• 400ksps, multichannel, 10- and 12-bit ADCs offer low-power operation
and more
Amplifiers and Comparators
• Single-supply, 400MHz op amps with disable have ultra-low distortion
and more
Analog Switches/Multiplexers
• 2Ω quad SPST analog switches optimized for ±5V applications
and more
(MAX4677/78/79) 13
Cable-TV IC
• Upstream CATV amplifier outputs 66dBmV
Power-Management ICs
• High-power step-up DC-DC converter integrates 10A switch
and more
Filter ICs
• Smallest 5th-order filters have lowest power
Battery Management ICs
• World’s smallest Li+ battery charger in SOT23
and more
• Quad voltage monitor requires no external components
and more
Interface ICs
• Triple RS-485 receivers include fault detection and ±15kV ESD protection
and more
(MAX3097E/98E) 18
Signal-Conditioner IC
• 16-bit signal conditioner for smart sensors operates at 2.4V
Hot-Swap Controller ICs
• Current-limiting hot-swap controllers include autoretry
and DualSpeed/BiLevel fault protection
(MAX4271/72/73) 20
Level Translators
• Low-voltage SIM/smart-card level translators in µMAX package
and more
Voltage References
• Low-dropout, 20ppm/°C references deliver 5mA and require no output capacitors
and more
Temperature Sensor ICs
• First SOT23 dual-temperature comparators need no external components
Fiber-Optic ICs
• 2.7Gbps multiplexer/buffer simplifies redundancy
and more
Wireless ICs
• Tiny chip-scale power amplifier for Bluetooth Class I applications
and more
News Briefs
Maxim Integrated Products, Inc., (MXIM) reported record net revenues of $256.6 million for its fiscal
fourth quarter ending June 24, 2000, a 60.9% increase over the $159.5 million reported for the same quarter a
year ago. Net income increased to a record $82.9 million in the fourth quarter, compared to $52.6 million last
year, a 57.8% increase. Diluted earnings per share were $0.26 for the fourth quarter, a 52.9% increase over the
$0.17 reported for the same period a year ago.
For the fiscal year, Maxim reported net revenues of $864.9 million, a 42.5% increase over the
$607.0 million reported last year. Net income increased 43.1% to $280.6 million in fiscal 2000, compared
to $196.1 million in fiscal 1999. Diluted earnings per share increased 37.5% to $0.88 in fiscal 2000 from
$0.64 in fiscal 1999.
Fourth quarter bookings were approximately $361 million, a 19% increase over the previous quarter’s
level of $304 million and an 83% increase over the fourth quarter of last year. Turns orders received in the
quarter were $108 million, a 13% increase over the $95 million received in the prior quarter (turns orders are
customer orders that are for delivery within the same quarter and may result in revenue within the same quarter
if the Company has available inventory that matches those orders). Bookings increased in all geographic
locations. There was significant growth in demand for the Company’s products targeting wireless and wired
communications, portable equipment, networks, and broad-based industrial applications. Fourth quarter
bookings by subcontract manufacturers exceeded third quarter levels.
Fourth quarter ending backlog shippable within the next 12 months was approximately $420 million,
including approximately $314 million requested for shipment in the first quarter of fiscal 2001. The Company’s
third quarter ending backlog shippable within the next 12 months was approximately $345 million, including
approximately $271 million that was requested for shipment in the fourth quarter. All of these backlog numbers
have been adjusted to be net of cancellations and estimated future U.S. distribution ship and debit pricing adjustments.
Jack Gifford, Chairman, President, and Chief Executive Officer, commented on the results: “Fiscal 2000
was an excellent year for Maxim. Our bookings, revenues, earnings, and new product introductions grew to
record levels. Cash and short-term investments increased over $126 million during the year after we repurchased
$257 million of our common stock and invested $45 million in properties and facilities and $131 million in
Mr. Gifford continued: “Demand for our products has never been stronger and continues to exceed our
expectations. End market bookings have continued to increase over the past nine months due in large part to a
significant increase in new customer equipment applications utilizing Maxim products. The acceptance of our
new products, the breadth of our proprietary product lines, and the increasing demand for our products from
emerging markets also contributed to this growth. While bookings growth rates remain strong, turns orders as a
percent of bookings have come down from 41% in the fourth quarter of fiscal 1999 to more historical levels of
30% in the fourth quarter of fiscal 2000. We expect turns orders to stay at this level as customers are placing
more of their orders for delivery within the next three to six months. These orders remain within our 12-month
booking schedule.”
Mr. Gifford concluded: “We did an excellent job of meeting our product introduction goals this year. We
introduced a record 383 products during our product introduction year ending July 22, 2000, compared to 284
products last year. The 35% increase year over year bodes well for Maxim’s long-term growth expectations.
These products are key to our achieving future revenue growth targets and position Maxim as one of the premier
analog companies in the world.”
ICs help implement
a trim-free VCO1
(Part 2)
occur even with a good first-order design because of the
trade-offs that exist among current consumption, startup
margin, frequency tuning range, and phase noise.
A major disadvantage of discrete IF VCO designs is the
amount of PCB area needed. Much effort must be
expended in optimizing the layout to below 6mm x 10mm.
Furthermore, the PCB layout has a critical effect on the
VCO’s performance and design accuracy. The layout
contains parasitic capacitances and inductances that affect
the oscillation frequency and must therefore be taken into
account to implement the oscillator properly. Parasitic
elements often cause an undesired shift in the nominal
oscillation frequency, which causes greater designcentering errors and ultimately forces a need for greater
tuning range to account for those errors.
A new family of integrated circuits can ease the task of
developing compact, fixed-frequency, voltage-controlled
oscillators (VCOs) for IF applications.
Designing a VCO for use with a fixed intermediatefrequency (IF) can be daunting. Fortunately, VCO ICs
from Maxim (MAX2605–MAX2609) can simplify the
task. Compared to conventional discrete-device VCOs, the
Maxim parts cost less and require less PC board space.
The MAX2605–MAX2609 IF VCO family offers a better
alternative. These five ICs are designed for low-power,
fixed and single-frequency portable wireless applications
with IF frequencies in the 45MHz to 650MHz range.
Much of the required circuitry is included on chip; only
the tank inductor (which establishes the oscillation
frequency) is external.
In a traditional IF VCO design, the oscillator core and
output buffer stage are formed by discrete transistors,
resistors, capacitors, and inductors (Figure 1). The tank is
built from a network consisting of the frequency-setting
inductor, varactors, coupling capacitors, and feedback
capacitors. The output stage uses reactive elements to match
the output impedance to a particular load impedance.
Once you choose the correct external inductance value,
the IC guarantees that some level within the tuningvoltage range (+0.4VDC to +2.4VDC) will tune in the
corresponding frequency. The IC’s tuning-voltage input
can be driven directly from the loop-filter output
following a phase-locked loop (PLL). MAX2605–
MAX2609 ICs are designed for supply voltages in the
+2.7VDC to +5.5VDC range, and the supply voltage
connection does not require special regulation for proper
operation. Each IC comes in a tiny, 6-pin plastic SOT23
package (Figure 2).
To ensure a successful design, the component values must
not only establish a desired nominal oscillation
frequency, they must also guarantee an adequate tuning
range, proper biasing, oscillator startup under all conditions, and proper output-stage performance. Problems can
Figure 1. This schematic shows an IF VCO implemented with discrete
circuit elements.
Figure 2. The MAX2605–MAX2609 IF VCO ICs come in a 6-pin
surface-mount SOT23 package designed to occupy minimum
PCB space.
1A similar article appeared in the August 2000 issue of Microwaves & RF magazine.
The MAX2605 tunes from 45MHz to 70MHz, with
-117dBc/Hz phase noise at 100kHz from the carrier. For
the other devices, these parameters are: 70MHz to
150MHz tuning with -112dBc/Hz phase noise at 100kHz
from the carrier (MAX2606), 150MHz to 300MHz with
-107dBc/Hz (MAX2607), 300MHz to 500MHz with
-100dBc/Hz (MAX2608), and 500MHz to 650MHz with
-93dBc/Hz (MAX2609).
adapted so that all the oscillator circuit elements (except
the inductor) could be integrated within the IC.
Integrating nearly the entire oscillator on chip provides all
the desired operating objectives of a good VCO: proper
oscillator startup, wide frequency range, required tuning
characteristics for trimless operation, controlled current
consumption, and biasing that was independent of
temperature and the power-supply voltages.
The frequency tuning range, biasing, startup, and other
oscillator characteristics are all managed within the IC,
eliminating the design headaches typically associated
with VCO design. An on-chip varactor and capacitors
simplify IF VCO design by eliminating the need for
external tuning elements. A graph of inductance versus
oscillation frequency (see the MAX2605–MAX2609 data
sheet) further simplifies the task of choosing an external
An off-chip inductor allows the VCO to be applied over a
very wide range of operating frequencies. On-chip capacitance remains the same, but changing external inductance values modifies the resonant frequency of the oscillator tank circuit. If the inductor has a minimum quality
factor (Q), the phase-noise and startup behavior can be
guaranteed (Figure 3).
To implement this new approach, the IC technology
needed a full complement of active and passive elements
to support construction of the oscillator circuit shown.
Specifically, the process technology had to provide highfrequency transistors, high-Q capacitors, high-Q varactor
diodes with high capacitance ratios, and PNP or PMOS
The MAX2605 family provides several important new
benefits for RF designers. The ICs are designed to create
VCOs that are trimless and do not need external adjustments. To accommodate the anticipated range of system
IFs found in dual-conversion systems, they are designed
to cover a wide range of application frequencies. In
addition, they have a flexible output interface to help
reduce the cost of IF VCOs and shrink the size of the
final design.
The MAX2605–MAX2609 are fabricated on a silicon
BiCMOS process developed specifically for RFICs that
include monolithic oscillator structures. This process
features PNP, NMOS, and PMOS devices, NPN transistors with transition frequencies (f T ) of 25GHz, lowseries-resistance varactor diodes with better than 2:1
capacitance ratio (for tuning voltages from 0.4V to 2.4V),
very high-Q metal-insulator-metal (MIM) RF capacitors,
precision thin-film resistors, and three layers of metal.
Because the MAX2605–MAX2609 represent a new
concept in VCOs, they required a fundamentally new
circuit approach to achieve the product objectives. Maxim
devised an oscillator scheme based on the reliable and
flexible Colpitts oscillator structure. This topology was
Figure 3. This simplified circuit diagram of the MAX2605–MAX2609 VCO ICs shows that only an external inductor is necessary to complete the
resonant circuit, which sets the oscillation frequency.
This full complement of devices allowed implementation
of the complete IC. The VCO design required careful and
extensive computer simulations, including multiple
design iterations between various aspects of performance
to ensure that all specifications and requirements could be
guaranteed over all operating conditions.
The nominal operating frequency (fNOM) desired for the
VCO is determined solely by the effective external inductance value at IND (pin 1), as determined by a curve
(Figure 5).
The inductance value (LF) required for a desired operating
frequency will not necessarily coincide with any of the
standard values for surface-mount-technology (SMT)
inductors, which typically increase in steps that differ by a
factor of approximately 1.2. To achieve the desired value
in such cases, the inductance must be constructed from
two inductors, LF1 and LF2. LF1 should be chosen as the
nearest standard value below the desired value. Then,
choose LF2 as the nearest standard value just less than
LF - LF1. LF1 should adhere to the minimum Q requirements, but LF2 can be implemented as a lower cost thinfilm SMT type. Because its value is less than 20% of the
total, its lower Q has only a small effect on the overall Q.
Finally, to guarantee that the oscillator possessed a sufficient frequency-tuning range to account for the shift in
operating frequency caused by component tolerances,
Maxim elected to perform production testing on the
devices and guarantee a set of frequency limits. These
limits provide MAX2605–MAX2609 users with a guaranteed set of high- and low-frequency tuning limits
(fMAX and fMIN), in which passing ICs have a frequency
of oscillation (fOSC) ≤ fMIN at a tuning voltage (VTUNE)
of 0.4V, and fOSC ≥ fMAX at VTUNE = 2.4V. Assuming
an external inductor with ±2% tolerance, including
temperature drift, and a small design centering error
(<0.5%), this testing guarantees that the VCO always
tunes to the operating frequency selected by the inductor,
without adjustment of the external inductance value. The
result is a trimless VCO design.
It is also permissible to adjust the total inductance value
by implementing small amounts of inductance with PCB
traces. For MAX2608/MAX2609 circuits, the inductance
value for LF2 is sometimes more precisely implemented
as a PCB trace shorted to ground than as an SMT
inductor. Once the required inductance value is established at pin IND, the VCO is guaranteed to tune to this
oscillation frequency over all component variations,
operating temperatures, and supply voltages.
MAX2605–MAX2609 applications are highly simplified
and easy to understand. Two simple steps are involved:
1) Select and implement an external inductance to set the
desired oscillation frequency.
MAX2605–MAX2609 VCOs include a differential output
amplifier after the oscillator core. The amplifier stage
provides valuable isolation and offers a flexible interface
to IF functions such as a mixer and/or a PLL prescaler.
2) Resistively or reactively match the output stage to the
load (Figure 4).
Figure 4. This simple schematic represents a typical application for the MAX2605–MAX2609 VCO IC.
VCC = 2.75V, TA = +25°C,
150 160 170 180 190 200
220 230 240
250 260 270 280 290 300
Figure 5. This plot contains values of the required total tuning inductance (LF) as a function of desired oscillation frequency (150MHz to 300MHz)
for the MAX2607 VCO IC.
The output can be taken single ended or differentially, but
the maximum output power and lowest harmonic output
is achieved in the differential-output mode. Both opencollector outputs (OUT- and OUT+) require a pullup
element to the collector voltage (VCC). The output stage
may be applied with a pullup resistor or inductor. A
pullup resistor is the most straightforward method of
forming an interface to the output and works well in
applications that operate at lower frequencies or require
only a modest voltage swing.
A comparison of the design time needed to apply each
approach reveals a dramatic difference. The classical/
discrete approach shown is very design intensive, and the
successful development of a discrete IF VCO may require
many weeks. Several iterations are likely before reaching
a robust, manufacturable design. On the other hand, the
MAX2605–MAX2609 let you design the VCO in
minutes and then verify and test it in an afternoon!
Because the MAX2605–MAX2609 solve the problems of
frequency tuning range, biasing, and startup, they
completely eliminate the difficult tasks typically associated with a VCO design. You need only select an external
inductance value based on the desired oscillation
frequency, and the output load. This task is easily accomplished by reading the desired inductance value from a
graph supplied on the MAX2605–MAX2609 data sheet.
A reactive power match is required for operating frequencies above the 3dB bandwidth of the load-resistance/
capacitance network and/or when a greater voltage swing
or output power is desired. The matching network is a
simple circuit with a shunt inductor and series capacitor.
To provide DC bias for the output stage, the inductors are
connected from OUT- and OUT+ to VCC, and the series
capacitors are connected from OUT- and OUT+ to the
load. Values for the inductor and capacitor are chosen
according to the operating frequency and load impedance.
The output is applied like any conventional differential
output. The only constraints are the need for a pullup to
VCC and a limit to the voltage swing at OUT- and OUT+.
In bill-of-materials cost, the MAX2605–MAX2609 are
comparable to the traditional discrete IF VCOs. As for
manufacturing, Maxim’s parts may support even less
expensive IF VCOs—as a consequence of having fewer
components to place and a $0.03 savings per component.
Maxim leads the
way in ESD
of metalization or other layers. ESD strikes can also find
paths into the core of an instrument. Somewhat like a
lightning strike, ESD will course through the circuit until
its energy is dissipated, often with unexpected effects.
Where does high voltage come from?
Mechanically separating two materials creates electrostatic charge. The surfaces of these otherwise neutral
materials are electrically double layered to varying
degrees, meaning that the outer layer might have a
majority of electrons balanced by positive charge in the
bulk of the material. Other materials exhibit the opposite
surface charge. When materials with opposite surface
charges come in contact, a transfer of electrons leaves one
material with a net negative charge and the other with a
net positive charge. Called triboelectric generation, this
effect is the basis of static generation and transfer.
Electrostatic discharge (ESD) is often found to be the root
cause of equipment failure on the factory floor and in the
field. Such failures can be difficult to track down when
they masquerade as other types of failures, as they often
do. In manufacturing, for instance, the yield loss at final
test might be traced to a bad component or subassembly
and then (with further investigation) associated with an
OEM manufacturing or test process that subjects the part
to ESD.
Early field failures and post-installation problems in industrial equipment are often caused by ESD during installation.
The most insidious ESD damage is that which degrades the
performance of an instrument but (at least initially) does not
affect its operation in an obvious way. Such events can
cause erratic or nonlinear operation immediately but may
not produce a “hard” failure for months or years.
The triboelectric series shown in Table 1 positions
materials like glass and nylon at the positive end and
silicon and teflon at the negative end. The materials’
conductivity also affects their ability to build up a surface
charge. For many materials, the conductivity or surface
resisitivity is strongly dependent on humidity. Low
humidity promotes low conductivity, which maintains the
localized charges by preventing them from moving.
This article explains how to protect your products from
ESD. It outlines the standard test methods required by the
electronics industry, offers some common techniques to
protect against ESD, and highlights some of Maxim’s
ESD-protected devices. With careful design, these
devices can improve product quality while saving
money and your company’s reputation.
Table 1. Triboelectric series
Damage potential
A photomicrograph (Figure 1) shows the damage
sustained by a competitor’s RS-232 interface IC after
exposure to an ESD strike of 15kV (a common test level).
The result is a gross failure that is easily visible because
the overstress actually vaporized metalization on the chip.
In other cases, the investigation of invisible failures in the
gate-oxide layers or buried layers requires careful removal
In the real world, static high voltage is usually produced
by the interaction of people and their surroundings.
Imagine a person sitting at a formica table in a plastic
chair, wearing wool slacks and socks, leather shoes, a
cotton shirt, and silk tie. This soup of triboelectric
materials defies quantitative analysis, but one can imagine
it responsible for some serious charge build-up. Several
accepted models describe a charged human body for
different situations. The most generic model (Figure 2)
assumes a 100pF capacitance charged to 15,000V and a
1500Ω series resistance.
Figure 1. This photomicrograph shows gross ESD damage to an
unprotected RS-232 receiver.
(NOTE 6)
Figure 2. When discharged, this circuit (the Human Body Model)
produces a very fast rise time with current peaks of
15kV/1.5kΩ—over 10A!
(MIL-STD 883,
METHOD 3015.7)
(IC-121, EIAJ)
R1 (Ω)
1M TO 10M
50M TO 100M
R2 (Ω)
1500 ± 1%
C1 (pF)
100 ± 10%
200 ± 5%
Figure 3. Substituting different component values as shown yields
discharge circuits known as the Human Body Model, the
Machine Model, and the IEC 1000-4-2 Model (human
holding a metallic object).
Test methods and standards
Two methods commonly used for testing the ESD susceptibility of integrated circuits have been adapted for endequipment testing as outlined in the next section. The
oldest method, MIL-STD-883 Method 3015.7, was
developed as an aid in understanding the precautions
necessary for packaging and handling ICs. This method
tests each package pin against other groups of pins and
classifies the device according to the lowest voltage for
which failure occurs.
These two tests are for ICs. Other specific tests govern
the exposed interfaces of end equipment. For example, IC
pins exposed to the outside world through connectors can
encounter ESD even when mounted on a PC board within
an enclosure. ESD exposure is less likely for the other
pins, which are connected to circuitry on the board.
For this class of IC, a test method such as Method 3015.7
(which tests pin combinations) does not provide an
adequate representation of ESD susceptibility for the
input/output (I/O) pins. The Machine Model and Method
3015.7, which offer ratings according to the lowest
voltage failure on any pin, may not do justice to the
higher levels of internal ESD protection required by the
I/O pins (and provided by some manufacturers). A device
might have I /O pins that withstand ±15kV and non-I /O
pins that fail at ±2kV. With the methods described above,
the resulting ESD rating could be less than ±2kV.
Fortunately, however, better test methods are now
available for rating I/O pins.
The applied signal in this test is a current waveform
derived from a circuit called the Human Body Model
(Figure 2), which simulates the capacitance and source
impedance typical of a human body. Circuit layout is
critical because the actual waveform delivered at the IC
depends also on parasitic inductance and capacitance
associated with the test connections and PC board. The
resulting current waveform represents the ESD that
occurs when a person touches an object such as an IC.
The other method, which differs from the above only in
the values for R and C, was developed by the Electronic
Industries Association of Japan (EIAJ). Called IC-121 and
based on a circuit called the Machine Model (Figure 3), it
applies a current waveform similar to that produced when
an IC makes contact with its handling machinery. By
mimicking the ESD events caused by charges that accumulate on moving parts, the waveform simulates the static
discharges seen during machine assembly.
New ESD tests for I/O ports
An I/O port allows communication with other pieces of
equipment. I/O ports for ICs comprise logical groups of
pins that give access to equipment external to the system
containing the IC. These pins are subject to static
discharge and other abuse as operators connect and
disconnect cables from the system. For the I/O pins of an
external interface IC, an ideal test method for ESD
susceptibility should:
The two methods are complementary, so you shouldn’t
choose one over the other. Because ESD can affect ICs
during manufacturing, during PC board assembly, and
after the end product is put into service, a test based on
the Human Body Model and the Machine Model together
provides adequate assurance regarding the IC’s tolerance
for the rigors of manufacturing and product life.
• Test the I/O pins only in ways that simulate exposure
to ESD events in actual equipment.
simple shunt capacitor from input to ground. The idea is
that a capacitor of sufficient value will absorb an ESD
discharge without exceeding the ESD rating of the
attached IC pin. To illustrate, consider an IC pin exposed
to the outside world, with an ESD rating of 2kV.
• Apply test waveforms that model electrostatic
discharges produced by the human body. Different
circuit models specify different values of amplitude,
rise/fall time, and transferred power.
• Test the IC with and without power applied.
The IEC 1000-4-2 Model specifies a 150pF capacitance
charged to 15kV. If a 1500pF capacitance is added to the
exposed pin, it will charge to a maximum equal to 1/10 of
the test voltage (1.5kV). Because this level is below the
IC’s ESD-protection rating, one assumes that all is well.
This method is widely used, but it involves a simplistic
view of the physics involved. It provides some protection
if you exercise extreme care in the circuit layout,
provided that the circuit operation is not affected by either
the necessary capacitance or parasitic inductance. To
emphasize the sensitivity to layout, consider that a 1cm
trace on a PC board has about 7nH of inductance. When a
30A current pulse with 1ns rise time (the IEC 1000-4-2
waveform, Figure 4) is applied to 7nH, it produces a
voltage spike of 210V for each centimeter of ground path.
• Define IC failures to include latchup (a momentary loss
of operation) as well as catastrophic or parametric
failure. Latchup is considered a failure mechanism
because, if left undetected, it can lead to reliability
problems and system malfunctions.
Two methods—both compliant with the requirements
listed—have seen increasing use by equipment manufacturers in testing the ESD susceptibility of I /O ports
(Figure 3). The first is a modification of Method 3015.7,
MIL-STD-883. It makes use of the same circuit model
and waveform as the original method but applies ESD
pulses only to the I /O pins of a device. Its intent is to
simulate the fault currents seen by an IC installed on a
board and operating in the target system. The second
method is IEC 1000-4-2, which has become the world
standard. It specifies a higher capacitance and lower resistance than that specified in Method 3015.7. IEC 1000-4-2
is universally applied in testing end-equipment interfaces
(Table 2). Note that Maxim’s analog switches and
RS-232/RS-485 interface ICs comply with these ESD
standards, without the need for external components.
Resistor protection
Resistor protection is added in series to the interface pins.
This resistance limits peak currents and helps dissipate some
of the power in a transient. Similar to capacitor protection,
precautions should be taken to ensure that circuit operation is
not adversely affected by this increased impedance. Another
caveat is that resistors themselves can be ESD sensitive.
Metal-film resistors are fabricated with methods similar to
semiconductor metalization and often have similar ESD limi-
Table 2. IEC 1000-4-2 classification of four
voltage ranges
1 AT 30ns
ESD-protection methods
Protecting an interface from ESD damage is the
designer’s responsibility. The industry offers a choice of
several methods, each with certain strengths and weaknesses. Lots of misunderstanding and black magic
surround ESD remedies, and the following discussion is
intended to dispel some of that mystery.
1 AT 60ns
tR = 0.7ns TO 1ns
Capacitor protection
Figure 4. Parameters for this ESD waveform (rise time, peak current,
amplitude at 30ns, and amplitude at 60ns) are specified by
IEC 1000-4-2.
This method is common in high-volume consumer and
automotive equipment. It protects the input pins with a
tations. The parasitic capacitance of these series resistors can
also be an issue. A narrow spike, through even a few picofarads, can wreak havoc on an IC input.
Also scheduled for introduction is a unique ESD-protected
interface for data cables. Data cables for cellular phones
usually include an RS-232 interface in the cable rather than
the phone. Thus, ESD protection for this application is
required not just on the RS-232 side of the interface IC but
on the logic side as well. The MAX3237E is the only IC
available that offers a solution to this problem. It offers a
complete 5-transmitter, 3-receiver interface (like a
modem). Maxim has plans to introduce additional RS-232
interface ICs with this double ESD protection for other
applications such as PDA cradles and other phone
Resistor-capacitor protection
This approach is a hybrid of the R and C protection techniques discussed above. Having two components per
interface pin consumes PC real estate while increasing
costs and decreasing reliability. RC networks are often
used for EMI suppression in concert with ferrite beads or
MOVs and TransZorb™ protection
RS-485 interfaces
Adding metal-oxide varistors (MOVs) or silicon
avalanche suppressors (TransZorbs) to I /O pins can be
very effective. They tend to be expensive, they can be
large, and they can add unwanted capacitance to an
interface. Similar to capacitor protection, these devices
require low-inductance (short) paths to ground.
Maxim is also the leader in ESD-protected RS-485 interfaces. After pioneering the use of ESD protection for such
devices, Maxim offers 17 products in this area, with many
more on the way. Significant in the last year was the introduction of the MAX3095/ MAX3096, which extend
Maxim’s robust ESD structures and low-power operation
to the venerable 26LS32 quad-receiver pinout. Also
released in the last year is a full line of 3.3V, ESDprotected, RS-485 interface ICs. Maxim innovations for the
MAX348_E family, for example, include ESD protection,
fractional unit loads, slew-rate limiting, and low power.
Layout guidelines for enhancing ESD protection
• Follow standard analog layout techniques, placing all
bypass and charge-pump capacitors as close as possible
to the IC (interface ICs especially).
• Include a ground plane on the PC board.
Analog switches
• Place the protection or IC as close to the I/O port as
Maxim was the first IC company to recognize the value
of ESD protection for analog switches and multiplexers
that serve as the interface to external systems in a host of
applications for which ESD protection is necessary. First
was a series of ESD-protected switches and multiplexers.
This series includes several low-voltage ICs with ±15kV
ESD protection: an 8-to-1 CMOS analog multiplexer with
4051 pinout (MAX4558), a 4-to-1 CMOS analog multiplexer with 4052 pinout (MAX4559), a triple SPDT
switch with 4053 pinout (MAX4560), and an SPST,
CMOS analog switch with 4066 pinout (MAX4551).
Protection internal to Maxim ICs
Maxim has invested a substantial effort in developing ICs
with internal ESD protection. Starting with RS-232 and
RS-485 interface ICs, these protected devices now
include several analog switches and the MAX681_ family
of switch debouncers. All withstand the application of
IEC 1000-4-2 ESD events directly to their I/O pins.
Maxim believes this is the best way to control ESD in a
system. It is robust, readily available, requires no external
real estate, and costs less than most alternatives.
A second series of devices, in SOT23 packages with
±15kV ESD protection, includes a single SPST-NO
switch (MAX4568), an SPST-NC switch (MAX4569),
and an SPDT switch (MAX4561).
Maxim offers a variety of ESD-protected RS-232 interface
ICs, representing every useful combination of drivers and
receivers. Included are ultra-low-power RS-232 devices
incorporating Maxim’s AutoShutdown™ feature. Several
new innovations have been introduced in the area of ESDprotected RS-232 interface devices this year. For example,
single RS-232 receivers and transmitters with full ESD
protection in tiny SOT packages (the MAX318_ series) can
be real problem solvers in small portable equipment.
1. Maxim Engineering Journal #25, “ESD Protection
for I/O Ports.”
2. Electrostatic Discharge Control, Owen J. McAteer,
McGraw Hill. 1989. ISBN 0-07-044838-8.
TransZorb is a trademark of General Semiconductor Industries, Inc.
AutoShutdown is a trademark of Maxim Integrated Products.
The MAX1280–MAX1287 (12-bit) and
MAX1080–MAX1087 (10-bit) analog-todigital converters (ADCs) offer 1, 4, and 8
channel options and 400ksps sampling rates.
Their serial interface connects directly to
SPI™, QSPI™, and MICROWIRE™ devices
without external logic. Ideal for portable data
acquisition and battery-powered applications,
these ADCs combine low-power operation
(1.5mA at 100ksps), excellent dynamic performance (SINAD > 70dB), and high speed
(400ksps) in packages as small as an 8-pin SO.
The analog inputs of these ADCs are software
configurable for unipolar/bipolar and singleended/differential operation. The full-scale
analog input range is set by the internal +2.5V
reference or by an externally applied reference
voltage between 1V and VDD. Operating from
an analog supply voltage in the +2.7V to +5.5V
range, the ADCs draw only 2.5mA at 400ksps.
Software power-down modes lower current
draw to 1.5mA at 100ksps. At even lower data
rates, supply current drops to <10µA.
The MAX1280–MAX1287 and MAX1080–
MAX1087 ADCs are available in 8-pin SO
packages and 16- and 20-pin TSSOP packages,
with prices starting at $3.88 (1000–up, FOB
12- and 10-bit
ADCs include
±1°C temperature
The MAX1298/MAX1299 and MAX1098/
MAX1099 are the first 12- and 10-bit
ADCs capable of measuring voltage, local
temperature, and remote temperature
without additional circuitry. Each includes
a ±1°C accurate sensor for local temperature measurement as well as signal-conditioning circuitry that enables the use of
diode-connected transistors for remote
temperature measurements.
The analog inputs can be configured
through the serial interface for temperature
measurement, single-ended voltage
measurement, and fully differential voltage
measurement. In the temperature-sensing
mode, internal bias currents pass through
either the internal sensor or an external
diode-connected transistor. No additional
circuitry is required for temperature
The MAX1099/MAX1299 operate from a
single +3V analog supply, and the
MAX1098/MAX1298 operate from a
single +5V analog supply. Quiescent
current is only 250µ A, and software
power-down modes further reduce the
supply current to <10µA at lower sampling
rates. All are available in 16-pin SSOP
packages, with prices starting at $2.68
(1000–up, FOB USA).
SPI/QSPI are trademarks of Motorola, Inc.
Smallest available
dual 8-bit DAC fits
in SOT23
The MAX5222 contains two buffered,
voltage-output, 8-bit DACs in a 3x3mm
8-pin SOT23 that requires 70% less board
space than comparable devices in 8-pin
SO packages. Operating from a single
2.7V to 5.5V supply, the MAX5222’s
ultra-low power consumption and small
size make it ideal for portable and batterypowered applications. Supply current is
<1mA and drops below 1µA in shutdown
mode. Shutdown further reduces system
power consumption by disconnecting the
reference-input pin from the REF pin.
The MAX5222’s 3-wire serial interface
allows clock rates up to 25MHz. The
serial input shift register is 16 bits long (8
bits of DAC input data and 8 bits for DAC
selection and shutdown control). DAC
registers can be loaded independently or
in parallel, at the positive edge of chip
select. Both DAC outputs can source and
sink 1mA while swinging to within
100mV of ground or VDD. Prices start at
$1.25 (1000–up, FOB USA).
10- and 12-bit
ADCs offer lowpower operation
MICROWIRE is a trademark of National Semiconductor
Octal, 13-bit
DAC has parallel
The MAX5270 includes eight 13-bit
voltage-output DACs and three separate
pairs of differential reference inputs on one
monolithic chip. For a reference voltage of
+4.096V to GND, the corresponding
output voltages have a full-scale range of
0V to +8.192V. The output amplifiers
remain stable while driving capacitive
loads up to 10,000pF, and the output glitch
amplitudes can be as low as 30mV during
major-carry transitions. The device also
offers low output noise (120nV/√Hz) and
low DC crosstalk (75µV).
The MAX5270 accepts 13-bit parallelloaded data from the external bus into one
of eight input registers, under the control
of WR, CS, and the DAC address pins
A0–A2. The DAC outputs are updated
upon receipt of new data into the DAC
registers. Each DAC output is buffered
with a gain-of-two amplifier, into which
an external DAC offset voltage can be
inserted through the SYSGND pins.
The MAX5270 is available in a spacesaving 44-pin MQFP package, with prices
starting at $22.50 (1000–up, FOB USA).
with disable
have ultra-low
The MAX4265–MAX4270 are singlesupply, voltage-feedback op amps capable
of driving 100Ω loads while maintaining
ultra-low distortion over wide bandwidths.
They offer an excellent spurious-free
dynamic range (SFDR): -88dBc or better
below 5MHz and -59dBc at 100MHz
(MAX4269). These devices operate from
a single +4.5V to +8V supply or dual
±2.25V to ±4.0V supplies. The input
voltage noise density is only 8nV/ √Hz,
making these op amps ideal for highperformance communications and signalprocessing applications that require low
distortion and wide bandwidth.
Dual 800kHz
op amp comes in
tiny 8-pin SOT23
The MAX4402 dual, rail-to-rail op amp in
a tiny 8-pin SOT23 package draws only
320µA of supply current per amplifier
while achieving an 800kHz gainbandwidth product. Ideal in space-limited
portable and battery-powered applications
that require low power without sacrificing
bandwidth or gain accuracy, it operates
from a single +2.5V to +5.5V supply. Its
output architecture is capable of driving a
2kΩ load to within 55mV of both supply
rails while maintaining a 110dB open-
1.8V, rail-to-rail I/O
op amps deliver
120dB AVOL and
drive 2kΩ loads
The MAX4292/MAX4294 (dual/quad) op
amps have Rail-to-Rail ® inputs and
outputs. Operating from a single +1.8V to
+5.5V supply, these op amps are ideal for
one- and two-cell, low-power, portable
applications. A 100dB power-supply
The MAX4265 (single) and MAX4268
(dual) are unity-gain-stable amplifiers
with gain-bandwidth products up to
400MHz. The single MAX4266 and dual
MAX4269 amplifiers provide bandwidths
up to 350MHz at a minimum stable gain
of +2V/V. The single MAX4267 and dual
MAX4270 provide a 300MHz bandwidth
at a minimum stable gain of +5V/V. Other
features include a 900V/µs slew rate and
±45mA output-driving capability.
For additional power savings, these amplifiers feature a low-power disable mode
that reduces supply current and places the
outputs in a high-impedance state. The
MAX4265/MAX4266/MAX4267 come in
a space-saving 8-pin µMAX package, and
the MAX4268/MAX4269/ MAX4270
come in a 16-pin QSOP. Prices start at
$2.05 (1000–up, FOB USA).
loop gain. The MAX4402 achieves
0.009% total harmonic distortion and is
unity-gain stable with capacitive loads up
to 400pF.
The MAX4402 is offered in space-saving
8-pin SOT23 and SO packages specified
over the automotive temperature range
(-40°C to +125°C). Prices start at $0.45
(100,000–up, FOB USA).
rejection ratio allows these op amps to be
operated directly from a single lithium-ion
(Li+) cell or from two to three NiCd,
NiMH, or alkaline cells, without
producing an excessive output error as the
cell voltage decays.
The MAX4292/MAX4294 achieve a
120dB open-loop gain while drawing only
100µA of supply current per amplifier.
They achieve a 500kHz gain-bandwidth
product, drive 2kΩ loads, and are unitygain stable for capacitive loads up to
100pF. Superior open-loop gain, excellent
3V/5V, 250MHz ADC
buffer amplifiers
achieve -87dBc
SFDR at 5MHz
The MAX4285–MAX4288 and MAX4387/
MAX4388 are single-supply, 250MHz op
amps in a space-saving 6-pin SOT23
package. The combination of single 3V/5V
operation, wide bandwidth, low -87dBc
SFDR (at 5MHz), and fast 6ns settling time
(to 0.1%) makes these op amps ideal for use
as preamps and drivers for a variety of highspeed, single-supply ADC applications in
communications and instrumentation.
These amplifiers operate from a single
+2.85V to +6.5V supply or dual ±1.425V
to ±3.25V supplies, and their input
common-mode range includes ground.
They have a large-signal -3dB bandwidth
of 200MHz, a slew rate of 350V/µs, and
an output current-drive capability up to
100mA. In addition, the MAX4285/
MAX4286/MAX4288/MAX4388 have
low-power disable modes that reduce
supply current and place the outputs in a
high-impedance state, making them ideal
for multiplexing applications.
The MAX4285/MAX4286 single amplifiers with disable are offered in spacesaving 6-pin SOT23 and 8-pin SO
packages. The MAX4287/MAX4387 dual
amplifiers are offered in 8-pin µMAX and
SO packages, and the MAX4288/
MAX4388 dual amplifiers (with disable)
are offered in 10-pin µMAX and 14-pin
SO packages. Prices start at $0.89
(1000–up, FOB USA).
load-driving capability, and an input offset
voltage of 400µV make these amplifiers
ideal for use as reference buffers.
The MAX4292 is offered in space-saving
8-pin µ MAX and SO packages. The
MAX4294 is offered in miniature 14-pin
TSSOP and SO packages. Prices start at
$0.23 per amplifier (quad, 50,000–up,
Rail-to-Rail is a registered trademark of Nippon
Motorola, Inc.
5MHz, SOT23 op
amp features
rail-to-rail I/O
2Ω quad SPST
analog switches
optimized for ±5V
The MAX4321 op amp combines a 5MHz
gain-bandwidth product and excellent DC
accuracy with rail-to-rail operation at the
output and both inputs. It draws only
650µA of quiescent supply current when
operating from a single +2.4V to +6.5V
supply or dual ±1.2V to ±3.25V supplies.
(Typical operation extends as low as
+1.8V or ±0.9V.) The MAX4321 remains
unity-gain stable with capacitive loads up
to 500pF and is capable of driving a 250Ω
load to within 200mV of either rail. Overdriven inputs do not produce an output
phase reversal.
The MAX4677/MAX4678/MAX4679
quad analog switches exhibit 2Ω (max)
RON when operating with ±5V supplies.
R ON is matched between channels to
within 0.3Ω (max), and is flat (to within
0.4Ω max) over the specified signal range.
Each switch handles rail-to-rail analog
signals, and off-leakage current is 0.1nA at
+25°C. Ideal in low-distortion applications, these switches are preferred for use
in automated test equipment (instead of
mechanical relays) because they have low
operating power, greater reliability, and
require less board space.
A rail-to-rail input common-mode voltage
range and output swing make the
MAX4321 ideal for low-voltage, singlesupply applications. Its low input offset
voltage (±1.2mV) and high slew rate
(2V/µ s) make it an excellent choice in
signal-conditioning stages for precision,
low-voltage data-acquisition systems.
The MAX4677 has four NC switches, and
the MAX4678 has four NO switches. The
MAX4679 has two of each and guarantees
break-before-make switching. Operating
from a single +2.7V to +11V supply or
dual ±2.7V to ±5.5V supplies, these
switches are ideal for use in digital card
applications and single-ended 75Ω
systems. All feature a separate logicvoltage input (+2.7V < VL < V+) that
allows independence between the logic
and analog supplies.
As a low-voltage, pin-for-pin upgrade for
the LMC7101, the MAX4321 offers five
times the bandwidth, twice the slew rate,
and approximately half the input voltage
noise density. It comes in a 5-pin SOT23
package specified for the extended-industrial temperature range (-40°C to +85°C),
with prices starting at $0.48 (1000–up,
reference in tiny
package simplifies
MAX4373/MAX4374/MAX4375 micropower devices combine a high-side
current-sense amplifier, a reference, and
one or two internal comparators in a tiny
(3mmx5mm) µ MAX (MSOP) package.
By including a reference and comparators
for user-programmable thresholds, these
The MAX4677/MAX4678/MAX4679 are
available in 16-pin DIP and TSSOP
packages, with prices starting at $1.87
(1000–up, FOB USA).
ICs vastly simplify the design of
over/undercurrent-protection circuits. The
combination of factory-trimmed gain and
external sense resistor allows the user to
select the full range of measured current.
Three factory-trimmed gains are available:
+20V/V (T version), +50V/V (F version),
and +100V/V (H version).
The MAX4373T/F/H set single-current
thresholds; the MAX4374T/F/H and
MAX4375T/F/H include an additional
comparator to allow for multiple thresholds and over/under thresholds. The
second comparator can also monitor a
system supply voltage. All devices operate
from a 2.7V to 28V supply and achieve
200kHz bandwidths (A V = +20V/V)
analog switches
provide ±15kV
ESD protection
The MAX4561 and MAX4568/MAX4569
are low-voltage, ESD-protected analog
switches. The MAX4568’s normally open
(NO) inputs, the MAX4569’s normally
closed (NC) inputs, and the MAX4561’s
single-pole/double-throw (SPDT) inputs
are protected against latchup or damage for
ESD up to ±15kV. Their COM inputs are
protected to ±2.5kV.
These switches operate from a single +2V
to +12V supply. For all, on-resistance
(R ON ) is 70Ω at 5V (120Ω at 3V),
matched between channels to within 2Ω
(max), and flat (over the specified signal
range) to within 4Ω (max). The switches
handle rail-to-rail analog signals, and their
off-leakage current is only 0.5nA at +25°C
(5nA at +85°C).
When operating with a 5V supply, the
digital inputs’ 0.8V to 2.4V logic thresholds ensure compatibility with TTL/CMOS
logic levels. The MAX4561 comes in a
6-pin SOT23 package, and the MAX4568/
MAX4569 come in a 5-pin SOT23
package. Prices start at $0.75 (1000–up,
while drawing only 60µ A of supply
current. Circuit architecture allows the
input common-mode voltage to range
from 0V to 28V, independently of the
supply voltage. Ground-sensing inputs
maintain linearity and keep the output
phase from reversing when the input
common-mode voltage is near ground.
This feature is useful during power-up or
power-down transients and during certain
input fault conditions.
The MAX4373T/F/H is offered in spacesaving 8-pin µ MAX and SO packages.
The MAX4374T/F/H and MAX4375T/F/H
are offered in 10-pin µMAX and 14-pin
SO packages. Prices start at $1.15
(1000–up, FOB USA).
SPST/SPDT analog
switches have
The MAX4641 and MAX4651 families of
analog switches operate from a single
+1.8V to +5.5V supply. The dual singlepole/single-throw (SPST) MAX4641/
MAX4642/MAX4643, single-pole/
double-throw (SPDT) MAX4644, and
quad SPST MAX4651/MAX4652/
MAX4653 switches have 4Ω (max) RON
with a 5V supply (8Ω with a 3V supply).
The single SPST MAX4645/MAX4646
have 2.5Ω R ON with a 5V supply. All
products feature RON matched between
channels to within at least 0.6Ω and flat
to within at least 1Ω over the specified
signal range. The switches offer fast
switching speeds: tON = 18ns (typ) and
tOFF = 12ns (typ). Off-leakage current is
≤0.1nA at +25°C, and quiescent power
consumption is ≤0.01µW. AC characteristics are excellent: ≤-100dB crosstalk at
1MHz, ≤-80dB off-isolation at 1MHz, and
0.018% THD.
The MAX4641 has two normally open
(NO) switches, the MAX4642 has two
normally closed (NC) switches, and the
MAX4643 has one of each. The
MAX4645 is a NO switch, and the
MAX4646 is a NC switch. The MAX4651
has four NC switches, the MAX4652 has
four NO switches, and the MAX4653 has
two of each. All MAX4641 family
devices are available in a small 8-pin
µ MAX package, or a 6-pin SOT23
(MAX4644/MAX4645/MAX4646 only)
or 5-pin SOT23 (MAX4645/MAX4646
only), with prices starting at $0.60
(1000–up, FOB USA). All MAX4651
family devices come in 16-pin SO and
TSSOP packages, with prices starting at
$1.20 (1000–up, FOB USA).
analog switches in
SC70 package
The MAX4594–MAX4597 are singlepole/single-throw (SPST) CMOS analog
switches that operate from a single +2.0V
to +5.5V supply. MAX4594/MAX4596
switches are NO, and MAX4595/
MAX4597 switches are NC. MAX4596/
MAX4597 pinouts are optimized to
provide the highest off-isolation available
in an SC70 package.
Each switch guarantees 10Ω (max) RON
(5V operation), and 1.5Ω (max) flatness
over the analog signal range. All offer low
leakage current (0.5nA off-leakage),
-80dB off-isolation at 1MHz, 5pC (max)
charge injection, and fast switching (tON =
35ns max, tOFF = 40ns max). MAX4594–
MAX4597 switches are available in a
5-pin SC70 package, with prices starting at
$0.53 (1000–up, FOB USA.
NO 2
Wideband, quad,
2:1 analog
multiplexer has
The MAX4674 is a low-voltage CMOS
analog switch containing four 2:1 multiplexers/demultiplexers. Operating from a
single +5V supply, it exhibits a low 4Ω
(max) RON. The supply range is +1.8V to
+5.5V. RON matching between channels is
0.4Ω, and RON flatness over the specified
signal range is 0.8Ω. Off-leakage current is
only 0.5nA (max) at +25°C.
The MAX4674 handles rail-to-rail signals
and offers fast operation (tON = 18ns and
tOFF = 6ns). For 1MHz signals, crosstalk
is -114dB and off-isolation is -67dB.
Package options are the 16-pin QSOP,
TSSOP, and narrow SO, with prices
starting at $1.45 (1000–up, FOB USA).
Upstream CATV
amplifier outputs
The MAX3509 is a programmable power
amplifier for use in CATV upstream applications. It operates in the 5MHz to 65MHz
frequency range, requires a single supply,
and generates up to 66dBmV QPSK
through a 1:1 transformer. Its variable gain
is controlled in 1dB steps through a 3-wire
serial data bus.
A transmit-disable mode places the
MAX3509 in a high-isolation state,
shutting down all analog functions to
minimize power consumption and output
noise between bursts in a TDMA system.
(Transmit-disable mode lowers the supply
current to 7.8mA.) When entering and
leaving this mode, transients are held to
25mV nominal at full gain.
An additional power-down mode
(shutdown) disables all circuitry and
reduces the supply current below 1µ A.
The MAX3509 is available in a 20-pin
TSSOP-EP package specified for the
extended-industrial temperature range
(-40°C to +85°C). Prices start at $4.75
Fast, 4-channel
analog multiplexer
has 4Ω RON
The MAX4634 is a fast (30ns tON, 13ns
tOFF), low-voltage (1.8V to 5.5V supply),
4-channel analog multiplexer with 4Ω
(max) R ON . R ON matching between
switches is 0.3Ω (max), and RON flatness
over the specified signal range is 1Ω
(max). Off-leakage current is only 0.1nA
(max) at +25°C, and each switch handles
analog signals in the V+ to ground range.
All digital inputs have 0.8V and 2.4V
thresholds to ensure TTL/CMOS compatibility.
The MAX4634 comes in a 10-pin µMAX
package, with prices starting at $0.95
(1000–up, FOB USA).
For applications that require less than fullpower capability, the MAX1709’s
programmable soft-start and current
limiting let you save size and cost by
scaling down the external components.
Low quiescent power consumption
(<1mW) extends the MAX1709 operating
time in battery-powered systems. In
addition to conventional on/off logic
control, two on/off control inputs allow
simple push-on/push-off control through a
momentary pushbutton switch.
By constraining the switching-noise
spectrum to the 600kHz fundamental and
its harmonics, the MAX1709’s fixedfrequency PWM operation enables easy
postfiltering for noise reduction. For even
tighter control of the noise spectrum, you
can synchronize the clock to an external
frequency in the 350kHz to 1MHz range.
The MAX1792 low-dropout linear regulator
(LDO) operates from a 2.5V to 5.5V supply
and delivers a guaranteed 500mA load
current with low 130mV dropout voltage.
The output voltage has high accuracy
(±1%). It comes preset to 1.5V, 1.8V, 2.5V,
3.3V, or 5V, or can be adjusted from 1.25V
to 5.0V with an external resistor divider.
An internal PMOS pass transistor allows
the low supply current (80µA) to remain
independent of load, making this device
ideal for portable battery-operated
equipment, such as personal digital assistants (PDAs), cellular phones, cordless
phones, base stations, and notebook
Other features include an active-low, opendrain reset output with 4ms timeout period
(indicating when the output is out of regulation), a 0.1µ A shutdown mode, and
short-circuit and thermal-overload protection. The MAX1792 comes in a miniature,
1.3W, 8-pin power-µMAX package with
metal pad underneath. Prices start at $1.15
(1000–up, FOB USA).
VIN = 2.5V TO 5.5V
Preassembled evaluation kits with recommended components are available to help
reduce design time. The MAX1709 is
specified for the extended-industrial temperature range (-40°C to +85°C), with prices
starting at $3.57 (1000–up, FOB USA).
12V, low-dropout
linear regulators
have low 2µA IQ
The MAX1725/MAX1726 are linear regulators ideal for low-power applications
that demand the longest possible battery
life. These devices offer ultra-low supply
current (2µA) and low dropout voltage.
Unlike PNP-based designs, the MAX1725/
MAX1726 have PMOS pass elements that
The MAX1793 LDO operates from 2.5V
to 5.5V and delivers a guaranteed 1A load
current with a low 210mV dropout
voltage. The high-accuracy output voltage
(±1%) is preset to 5V, 3.3V, 2.5V, 2V,
1.8V, or 1.5V, or can be adjusted with an
external resistor divider.
An internal PMOS pass transistor allows
the MAX1793 to draw only 125µA of
supply current, making it ideal for use in
battery-powered equipment. Shutdown
current is 0.1µA, and output noise is only
115µVRMS. Other features include a builtin reset output, low-power shutdown, and
protection against short circuits and
thermal overload. The MAX1793 comes in
a 1.5W, 16-pin power TSSOP package,
which is only 1.1mm high and 30%
smaller than a SOT223 package. Prices
start at $1.50 (1000–up, FOB USA).
maintain an ultra-low 2µA supply current
throughout their operating range,
including dropout. Despite their low
power consumption, they have tight
output accuracy (1.5%), and they achieve
good load-transient response with just 1µF
of output capacitance.
The wide input voltage range of
MAX1725/MAX1726 regulators (2.5V to
12V) makes them an excellent choice for
systems powered by a 9V battery or by
two Li+ cells. The regulators include
1A linear regulator
offers low dropout
and low IQ
MAX1793 toc07
The MAX1709 step-up DC-DC converter
sets a new standard of space savings for
high-power devices of its type. Packing a
22mΩ, 10A power MOSFET in a small
16-pin narrow SO package, it delivers up
to 4A of output current (20W) when
stepping up from 3.3V to 5V. It accepts
inputs in the 0.7V to 5V range, and generates either a fixed 3.3V or 5V, or an
adjustable output in the 1.25V to 5V range.
Linear regulator in
µMAX package
has 130mV
dropout at 500mA
step-up DC-DC
integrates 10A
1000 1200
protection against reversed batteries, short
circuits, and high temperature. Output
currents are guaranteed to 20mA.
The MAX1725 output is adjustable from
1.5V to 5V using an external resistor
divider, and the MAX1726 comes with its
output factory preset to 1.8V, 2.5V, 3.3V,
or 5V. Both devices come in a miniature
5-pin SOT23 package, with prices starting
at $0.82 (1000–up, FOB USA).
World’s smallest
power ICs for
CDMA handsets
The MAX1798/MAX1799 system power
supplies are designed specifically for
CDMA cellular/PCS handsets and are
compatible with a variety of CDMA
chipsets. Each IC includes five low-noise
LDOs, a serial interface for controlling and
programming the output voltages, a reset
timer (140ms min), a watchdog input,
optional push-on/push-off power control,
and two high-current, open-drain outputs
for driving a vibrator motor and/or LEDs.
The two devices differ only in their serial
interface: the MAX1798 is compatible
with the 3-wire SPI interface, and the
MAX1799 is compatible with the 2-wire
I2C™ interface.
The main regulator output (LDO1) is rated
for 300mA, and the other four are rated for
150mA. All are optimized for high
LDOs feature
ultra-low IQ and
The MAX8880/MAX8881 LDOs have
ultra-low supply currents of 3.5µ A, yet
are capable of delivering up to 200mA.
These low-dropout devices operate with
inputs up to 12V and feature automatic
reverse-battery protection, making them
ideal for applications that require long
battery life.
Low supply current extends battery life in
applications with long standby periods.
Unlike PNP-based designs, these maintain
ultra-low supply current throughout the
operating range and in dropout. They
include protection against output short
circuits, reverse-battery connections, and
thermal overload. An internal power-OK
comparator (POK) indicates when the
output is out of regulation.
The MAX8880 output is adjustable from
1.25V to 5V using an external resistor
divider. The MAX8881 provides factorypreset output voltages of 1.8V, 2.5V,
3.3V, or 5V. Both are available in a
miniature 6-pin SOT23 package, with
prices starting at $0.86 (2500–up, FOB
accuracy, high channel-to-channel isolation,
low noise, and low dropout voltage. At
two-thirds of rated output current, the
dropout voltage is 75mV for LDO1 and
50mV for LDO2–LDO5. Each output
voltage can be independently enabled,
disabled, and programmed (to any of 32
levels from 1.8V to 3.3V) through the
serial interface. For added protection, each
LDO includes independent current limiting
and thermal overload circuitry.
The MAX1798/MAX1799 package—a
2.1W, space-saving 20-pin TSSOP
specified for the extended-industrial
temperature range (-40°C to +85°C)—
makes these devices the most compact
available for CDMA handset applications.
Prices start at $2.30 (1000–up, FOB
USA). Software and a preassembled evaluation kit (MAX1799EVKIT) are
available to help reduce design time.
I2C is a trademark of Philips Corp.
linear regulator
delivers 1A
The MAX8869 LDO operates from a 2.7V
to 5.5V input and delivers a guaranteed 1A
load current with 200mV dropout. Its ±1%
accurate output voltage level is preset at the
factory for 5V, 3.3V, 2.5V, 1.8V, or 1.0V,
or is adjustable from 0.8V to 5V using an
external resistor divider.
Internal MicroCap™ technology provides
stability using only a small 1µ F output
capacitor. The internal PMOS pass transistor provides exceptionally low 200mV
dropout voltage at 1A and suits the device
for use in networking and telecom
hardware as well as battery-operated
equipment. Other features include softstart capability, low-power shutdown,
short-circuit protection, and thermalshutdown protection. The MAX8869 is
available in a 1.7W, 16-pin TSSOP
package, only 1.1mm high and 30%
smaller than a SOT223. Prices start at
$1.65 (1000–up, FOB USA).
MicroCap is a trademark of Maxim Integrated
Smallest 5th-order
filters have lowest
The MAX7426/MAX7427 5th-order,
switched-capacitor, lowpass elliptic filters
are available in 8-pin µ MAX and DIP
packages. The proprietary µMAX package,
80% smaller than an 8-pin DIP, provides
the smallest 5th-order switched-capacitor
filters available. They operate from a single
supply of 5V (MAX7426) or 3V
(MAX7427), while drawing only 0.8mA of
supply current. While in shutdown, the
quiescent current drops to 0.2µA. Low cost,
small size, and low power make these
filters ideal for cost-sensitive portable
equipment that requires post-DAC or antialiasing filtering.
The MAX7426/MAX7427 provide 37dB
stopband rejection with sharp rolloffs and a
1.25 transition ratio. Corner frequencies
are clock tunable from 1Hz to 9kHz
(MAX7426) and 1Hz to 12kHz (MAX7427).
Two clocking options are available: selfclocking by means of an external capacitor,
or external clocking (for tighter control of
the cutoff frequency). The offset adjust pin
can either null the output offset (4mV typ)
or introduce a DC level shift at the output.
The MAX7426/MAX7427 are specified
for the commercial (0°C to +70°C) or
extended-industrial (-40°C to +85°C)
temperature range, with prices starting at
$0.70 (100,000–up, FOB USA).
World’s smallest
Li+ battery charger
in SOT23
The MAX1736 is a stand-alone charger
for single-cell Li+ batteries. Powered by
an inexpensive current-limited wall cube,
it operates with an external PFET switch
in a gated control scheme that allows the
entire charging circuit to remain cool—
unlike circuits based on heat-producing
linear-mode regulators. It fits in
cellular/PCS phone handsets and lowpower hand-held equipment, such as
PDAs and portable digital-audio players.
The MAX1736 offers better than 0.5%
accuracy for battery-regulation voltage. It
includes a complete state machine to
safely control the charging sequence and
an on-board precharge circuit that
prevents damage by charging near-dead
cells prior to the fast charge. Once the
battery-regulation voltage is reached, the
cell is topped off using a hysteretic
algorithm. This algorithm fully charges
the cell while eliminating errors due to
series resistance.
To accommodate a variety of wall cubes
and other input supplies, the MAX1736
operates with a wide 4.7V to 22V inputvoltage range. It automatically detects the
presence of an input supply, and if the
input power is removed, it automatically
powers down to minimize current drain
from the battery. A single ENABLE pin
permits simple charge control by an
optional microcontroller (µC).
For a similar Li+ charger that includes an
LED drive, internal safety counters, and
thermistor temperature monitoring,
consider the MAX1679 (available in an
8-pin µ MAX package). The MAX1736
comes in a tiny 6-pin SOT23 package
specified for the extended-industrial
temperature range (-40°C to +85°C), with
prices starting at $1.50 (1000–up, FOB
USA). A preassembled evaluation kit with
recommended external components
(MAX1736EVKIT) is available to help
reduce design time.
controller charges
Li+ batteries
The MAX1737 switchmode controller
charges one to four Li+ cells in series. It
provides a regulated charging current and
charging voltage, with a total voltage error
of only ±0.8% at the battery terminals. An
external N-channel switch and synchronous rectifier provide high efficiency for
input voltages up to 28V. The built-in
safety timer automatically terminates
charging when the adjustable time limit
has been reached.
Regulation of the voltage set point and
charging current is accomplished by two
control loops, which work together to
effect a smooth transition between voltage
and current regulation. To prevent
overload of the input supply and enable
use of a low-cost wall adapter, an additional control loop monitors and limits the
total current drawn from that supply.
The limit for battery-voltage regulation is
set between 4.0V and 4.4V per cell, and
the number of cells is set from one to four
by pin strapping. An external thermistor
monitors the battery temperature to
prevent charging when this temperature is
outside the acceptable range.
An evaluation kit (MAX1737EVKIT) is
available to help reduce design time. The
MAX1737 is available in a space-saving
28-pin QSOP package, with prices starting
at $2.85 (1000–up, FOB USA).
watchdog timers
come in SOT23
The MAX6369–MAX6374 watchdog timer
supervisory circuits are designed to increase
system reliability by supervising microprocessor (µP) activity and detecting codeexecution errors. When a system is not
operating properly, these devices signal a
fault condition by resetting or interrupting
the µP. Low supply current (5µA) makes
them ideal for battery-operated applications.
These watchdog timers provide 24 pinselectable timing combinations, and the
Quad voltage
monitor requires
no external
The MAX6338 quad voltage monitor is
designed to monitor multivoltage systems
in telecommunications, networking
equipment, storage devices, high-end
printers, and computers. When a monitored
voltage falls below its preset threshold, the
corresponding open-drain output notifies
the system by asserting an active-low
signal. The monitor deasserts when the
input voltage rises above the threshold.
A variety of voltage thresholds and tolerances are available to accommodate the
standard logic levels found in today’s
applications. These preset threshold
options include +5.0V, +3.3V, +3.0V,
+2.5V, +1.8V, and -5V. User-adjustable
options are also available to monitor
voltages different than those listed above.
Voltages of +5.0V, +3.3V, +2.5V, and
+1.8V can be monitored without adding
external components.
The internally trimmed thresholds and
weak internal pullups to VCC minimize the
need for external components. To provide
an easy interface to other devices, the four
independent open-drain outputs can be
overdriven by external voltages ranging
from 0V to +5.5V.
The MAX6338 operates from 2.5V to
5.5V and draws only 25µ A of supply
current. It is available in a small 10-pin
µ MAX package fully specified over the
extended temperature range. Prices start at
$2.50 (1000–up, FOB USA).
watchdog timeout period can be adjusted
from 1ms to 60s to accommodate most
systems. To allow for full initialization of
the system, a startup delay disables the
watchdog during power-up or during a
change in the watchdog timeout period.
Startup delays also range from 1ms to 60s.
The MAX6369–MAX6374 come in an
8-pin SOT23 package and require no
external components, making them ideal
for use in hand-held instruments and other
space-limited systems. Other applications
include embedded control systems, industrial controllers, and automotive systems.
Prices start at $0.98 (2500–up, FOB USA)
First backupbattery reset ICs
with chip-enable
gating in SOT
The MAX6365–MAX6368 are µP-supervisory ICs for digital systems that monitor
supply rails in the 2.5V to 5.0V range,
with ±2.5% reset-threshold accuracy over
temperature. When VCC falls below the
reset threshold, reset is asserted and maintained for at least 150ms after VCC rises
above the reset threshold. If V CC falls
below the reset threshold and is also less
than the battery backup voltage, the output
automatically switches from VCC to the
backup battery to power the system RAM
and/or real-time clock (RTC). Chip-enable
gating write-protects the RAM data during
these conditions.
These ICs are the first such devices with
chip-enable gating available in SOT
packages, which are approximately 70%
smaller than alternative packages.
Miniature packages and low supply
current (10µA) make the parts ideal for
portable applications. All devices are
available with a push-pull active-low reset
output, open-drain active-high reset
output, or open-drain active-low reset
output. Additional functionality includes a
manual-reset input (MAX6365), watchdog
input (MAX6366), battery-on output
(MAX6367), and auxiliary-reset input
(MAX6368). Available in an 8-pin SOT
package, they draw only 10µA of supply
current. Prices start at $1.88 (2500–up,
New SC70 poweron reset ICs
include manual
The MAX6711/MAX6712/MAX6713 µP
supervisory circuits monitor supply rails
of 2.5V to 5V in µP and digital systems.
Available in the miniature 4-pin SC70
package (half the size of a SOT package),
they reduce cost by eliminating external
components and adjustments. Each device
also includes a debounced manual-reset
Tiny, ultra-lowpower SC70
voltage detectors
ideal for portable
The MAX6375–MAX6380 voltage
detectors monitor battery, power-supply,
and regulated system voltages. Each
detector contains a precision bandgap
reference, comparator, and internally
trimmed resistors that set specified trip
threshold voltages. By monitoring nominal
system voltages from +2.5V to +5.0V
without the need for external components
or adjustments, they also provide excellent
circuit reliability and low cost.
The voltage detectors are differentiated by
their output logic configurations and preset
voltage thresholds. The MAX6375/
MAX6378 (push-pull) and MAX6377/
MAX6380 (open-drain) devices have
active-low outputs. The MAX6376/
MAX6379 have active-high push-pull
outputs. The MAX6375/MAX6376/
MAX6377 provide voltage thresholds
between 2.20V and 3.08V, in approximate
increments of 100mV. The MAX6378/
MAX6379/MAX6380 have voltage thresholds between 3.30V and 4.63V in approximate 100mV increments.
Ultra-low supply current (500nA) makes
the MAX6375/MAX6376/MAX6377 ideal
for use in portable equipment. All six
devices are available in a miniature SC70
package, with prices starting at $0.90
(2500 or 10,000 piece minimum, FOB USA).
Theses ICs feature 2.5% reset-threshold
accuracy over temperature. When supply
voltage declines below the device
threshold, the device asserts a reset signal
and maintains it for at least 140ms after
VCC returns above the reset threshold (or
until the manual reset is deasserted). The
MAX6711 has a push-pull active-low
reset output, the MAX6712 has a pushpull active-high reset output, and the
MAX6713 has an open-drain active-low
reset output. These ICs draw only 12µA
supply current, and the reset outputs are
guaranteed valid to 1.0V.
Prices start at $0.98 (2500 or 10,000 piece
minimum, FOB USA).
Triple RS-485
receivers include
fault detection
and ±15kV ESD
The MAX3097E/MAX3098E triple RS422/RS-485 receivers target motor-control
applications. Each receiver has an independent alarm output that warns of fault conditions at the receiver inputs. This alarm is
asserted when the receiver inputs are
shorted, open, out of their common-mode
range, or have a low differential voltage.
The MAX3097E and MAX3098E (A and
B grades) differ in the accuracy of their
differential fault thresholds. The devices
also feature capacitor-programmable,
delayed-alarm outputs to ensure error-free
fault detection even at slow transition rates.
The MAX3097E/MAX3098E operate from
a single 3.0V to 5.5V supply and guarantee
data transfers up to 32Mbps. To ensure
compliance with strict international ESD
requirements, the receiver inputs are ESD
protected up to ±15kV using the IEC 10004-2 Air-Gap Discharge method, to ±8kV
using the IEC 1000-4-2 Contact Discharge
method, and to ±15kV using the Human
Body Model.
MAX3097E/MAX3098E devices are
available in space-saving 16-pin QSOP,
SO, and DIP packages specified for the
commercial and extended temperature
ranges. Prices start at $3.56 (1000–up, FOB
A, A, B, B, Z, Z
12-BIT D/A
16-bit signal
conditioner for
smart sensors
operates at 2.4V
The low-power MAX1462 is a highly integrated, 16-bit signal conditioner for smart
sensors, capable of digitally correcting
sensor outputs over a wide temperature
range. It operates at 2.4V and draws only
310µA of supply current.
Internal to the chip is an RISC µ P,
EEPROM, 16-bit ADC, 12-bit DAC,
programmable-gain amplifier (PGA),
temperature sensor, and auxiliary op amp.
To produce the conditioned output, the
DSP combines the digitized input signal,
temperature-sensor output, and userprogrammed calibration coefficients stored
in the internal EEPROM. The result is
available both as a 12-bit digital word and
as a ratiometric analog voltage generated by
the internal 12-bit DAC. The uncommitted
op amp can be used for filtering the analog
output or implementing a 2-wire, 4–20mA
transmitter. The high-precision front end,
which includes a 16-bit ADC, 2-bit PGA,
and 3-bit coarse-offset DAC, resolves
differential input signals below 1µV.
The MAX1462 is perfect for hand-held,
low-power applications such as pressure
sensors, humidity sensors, and smart
batteries. It is readily adaptable for use in
automotive, industrial, and medical applications as well. Test features built into the
MAX1462 are designed to automate and
integrate the pretest, calibration, compensation, and final-test operations of traditional
sensor manufacturing. By eliminating
manual calibration methods, the device
saves significant manufacturing costs.
A dedicated cell library of more than 500
sensor-specific functional blocks enables
Maxim to quickly customize the
MAX1462 for unusual requirements associated with high-volume applications. The
MAX1462 is available in a space-saving,
9mmx9mm 48-pin TQFP package. Prices
start at $6.50 (1000–up, FOB USA).
Single +3.3V supply operation makes this
chipset ideal for low-voltage systems. The
MAX3170 is a 3Tx/3Rx transceiver for
The transmitter’s low-dropout output stage
provides ±3.7V (min) RS-232-compatible
output levels, while driving a load of 3kΩ
and 1000pF at 460kbps. Supply voltages of
+5V and -5V must be provided externally.
The MAX3314E’s SHDN input enables
an external signal to disable and three-state
the transmitter (receiver remains active),
while reducing the supply current to 1mA.
The MAX3314E is available in 8-pin
µ MAX and SO packages, with prices
starting at $1.18 (1000–up, FOB USA).
*Future product
The MAX3314E is a ±5V powered
transceiver compatible with the EIA/TIA232 standard. Its flow-through architecture
features one transmitter and one receiver,
protected to ±15kV using IEC 1000-4-2
Air-Gap Discharge, to ±8kV using IEC
1000-4-2 Contact Discharge, and to ±15kV
using the Human Body Model.
The MAX3171/MAX3172 receiver inputs
have 10µs deglitching circuitry that enables
unterminated operation. All devices have
true fail-safe receiver inputs that guarantee
logic high outputs when the bus is idle
or when the inputs are open or shorted.
The MAX3170, MAX3171/MAX3173,
and MAX3172/MAX3174 are available in
a 28-pin SSOP package, with prices for the
complete 3-piece chipset starting at $18.33
(1000–up, FOB USA).
1µA, 460kbps,
transceiver has
ESD protection to
The MAX3170, MAX3171/MAX3173*,
and MAX3172/MAX3174* form a multiprotocol chipset. This chipset is ideal for
networking applications, such as switches
and routers, that require compatibility with
many different protocols from a single
connector. The chipset provides pin- and
software-selectable DCE and DTE ports
compatible with protocols such as V.10,
V.35, V.28 (RS-232), and V.11 (RS449/
V.36, EIA530, EIA530-A, X.21). In
addition to these standards, the devices
have undergone compliance testing
performed and verified by an outside test
facility and compatible with the NET1,
NET2, TBR-1, and TBR-2 telecommunication standards.
transmitting high-speed clock and data
signals: to 10Mbps in V.11 or V.35 modes,
and to 240kbps in V.28 mode. The
MAX3171/MAX3173 are also 3Tx/3Rx
transceivers, but they transmit lower speed
control signals. The MAX3172/MAX3174
contain five termination networks designed
for use with the MAX3170, plus a fourth
transceiver for transmitting control signals.
Complete 3.3V
chipset supports
V.10, V.11, V.28,
and V.35 protocols
controllers include
autoretry and
fault protection
The MAX4271/MAX4272/MAX4273 ICs
make up a complete family of integrated
3V to 12V hot-swap controllers. They
enable safe insertion and removal of
circuit cards from a live backplane.
Because the circuit card’s discharged filter
capacitors provide a low impedance to the
live backplane, high-level inrush currents
from backplane to circuit card can burn up
connectors and components, or cause a
system reset by momentarily collapsing
the backplane power supply. By regulating inrush current to a preset limit,
these hot-swap controllers allow the
system to stabilize safely.
After the startup cycle is completed, two
internal comparators provide DualSpeed/
BiLevel™ protection against short
circuits, load glitches, and overcurrents.
The ICs respond to faults by disconnecting the load. They handle fault
recovery by unlatching (MAX4271),
autoretry (MAX4272), or programming
methods (MAX4273).
Additional features include an internal
charge pump that provides gate drive for
an external N-channel FET, startup
current regulation, and current-glitch
protection. Open-drain status outputs
indicate fault conditions.
The MAX4271 with latched fault protection and the MAX4272 with autoretry fault
protection are available in a space-saving
8-pin SO package, and the full-function
MAX4273 comes in 16-pin QSOP and SO
packages. All devices are specified for the
extended-industrial temperature range
(-40°C to +85°C) and have an absolute
maximum rating of 15V for extra protection against inductive kickback during
board removal. Prices start at $1.95
(1000–up, FOB USA).
DualSpeed/BiLevel is a trademark of Maxim
Integrated Products.
level translators
in µMAX package
The MAX1840/MAX1841 are level translators for smart cards and subscriber
identity modules (SIMs). They provide
level shifting and protection against ESD
for SIM and smart-card ports. The devices
integrate two unidirectional level shifters
for the reset and clock signals, a bidirectional level shifter for the serial data
stream, and ±10kV ESD protection for all
card contacts.
The MAX1840 SHDN control input aids
insertion and removal of SIM and smart
cards, and the MAX1841 system-side data
3.3V smart
regulator for
NICs requires
only 1µF output
The MAX1810 smart regulator is suitable
for use in Ethernet network interface cards
(NICs), modem cards, and other devices
compliant with peripheral component
interconnect (PCI) components. The
MAX1810 delivers an uninterrupted 3.3V,
with output currents up to 500mA, from a
5V main supply, a 5V standby supply, or a
3.3V auxiliary supply. When the main and
standby supplies both drop below 4.1V, an
internal switch connects the PCI system’s
3.3V auxiliary input to the MAX1810
20ppm/°C SOT23
references deliver
5mA and require no
output capacitors
The MAX6061–MAX6067 family of
three-terminal, series-mode precision
voltage references can save board space by
operating without an output capacitor.
Otherwise, they remain stable with
output/load capacitors as high as 1µ F.
These seven new devices have output
driver supports system controllers that lack
open-drain outputs. Logic-supply voltage
ranges are 1.4V to 5.5V for the controller
side and 1.7V to 5.5V for the card side.
Total supply current is 1.0µ A. Both
devices shut down automatically when
either supply voltage is removed. For a
complete SIM card interface, combine
the MAX1840 or MAX1841 with the
MAX1686H regulated charge pump,
which provides 0V, 3V, and 5V outputs.
The MAX1840/MAX1841 are compliant
with GSM test specifications 11.11 and
11.12. They are available in an ultra-small
10-pin µ MAX package that is only
1.09mm high and occupies half the area of
an 8-pin SO. Prices start at $1.55
(1000–up, FOB USA).
output. Low resistance in this internal
switch (only 0.18Ω) minimizes voltage
drop from the auxiliary supply.
The main and standby inputs generate the
3.3V output through CMOS linear regulators that feature excellent line and load
regulation. Their stability is guaranteed by
a 1µF ceramic output capacitor, and the
short-circuited output current is limited to
900mA. Thermal-overload protection turns
the MAX1810 off when the chip temperature exceeds +170°C. Special circuitry also
prevents a flow of reverse current from the
output to any inactive or low-voltage input.
The MAX1810 is available in a compact,
high-power (capable of dissipating 0.9W),
8-pin SO package specified for the
extended-industrial temperature range
(-40°C to +85°C). Prices start at $1.25
1000–up, FOB USA).
voltages of 1.250V, 2.048V, 2.500V,
3.000V, 4.096V, 4.500V, and 5.000V.
Each is available in two grades of output
temperature coefficient (20ppm/°C or
30ppm/°C), with initial accuracy grades of
0.2% and 0.4%.
Quiescent supply currents are low (90µA)
and virtually immune to voltage variations,
making these SOT23 voltage references
ideal for battery-powered instruments.
Usable as precision voltage regulators, the
MAX6061–MAX6067 references can
source 5mA of load current and sink 2mA.
Prices start at $1.35 (1000–up, FOB USA).
3-pin SC70 voltage
references are
smallest available
The LM4040/LM4041 are shunt-mode, 2terminal precision voltage references. Ideal
for space-critical portable applications,
they fit in a 3-pin SC70 package that
requires 40% less space than the already
tiny 3-pin SOT23 package.
Advanced design ensures stability with any
capacitive load, yet also ensures ease of use
by eliminating the need for an external
stabilizing capacitor. For an LM4041-1.2,
the minimum operating current is 60µA,
and the maximum is 12mA.
To ensure that the prime (A grade) parts
have an accuracy better than ±0.1% at
+25°C, the reference voltage is trimmed
during wafer sort using fuse and zener-zap
techniques. Each device offers four grades
(A, B, C, and D). The highest (A grade)
has 0.1% initial accuracy, B grade has
0.2%, and C grade has 0.5%. All have a
100ppm/°C tempco guaranteed from -40°C
to +85°C. The low-cost D-grade devices
have 1% initial accuracy with 150ppm/°C
The LM4041 has a fixed breakdown
voltage of 1.225V, and the LM4040
versions have breakdown voltages of
2.048V, 2.5V, 3.0V, 4.096V, and 5.0V.
Prices start at $0.45 (1000–up, FOB USA)
redundant systems
The MAX3781 dual multiplexer/buffer is
used in redundant high-speed serial data
paths. Each half of the dual part provides
a 1:2 buffer for creating duplicate outputdata paths, and a 2:1 multiplexer for
selecting from two alternate input-data
paths. This capability makes the device
ideal for implementing redundancy in
Dual 3.3V, 622Mbps,
4:2 crosspoint
switch enables
The MAX3640 is a 3.3V dual-path crosspoint switch for use at OC-12 (622Mbps)
data rates. It can receive and transmit
622Mbps LVDS signals across a backplane
with minimum jitter accumulation. The
device offers signal-path redundancy for
critical data streams, making it ideal for
SONET/SDH backplanes, digital crossconnects, and high-speed parallel links.
Each path in the MAX3640 incorporates
input buffers, multiplexers, a 2x2 cross-
serial-backplane and system-interconnect
applications up to 2.7Gbps.
Low total output jitter (only 15ps)
preserves data integrity. Signal output
levels are 1600mV (typ) for inputs as low
as 200mV. The MAX3781 operates with a
3.3V power supply and has a power-down
mode that disables unused buffer outputs.
The MAX3781 dual multiplexer/buffer
comes in a compact 48-pin TQFP package
and has on-chip terminations at all ports
compatible with 50Ω transmission lines.
Prices start at $6.49 (1000–up, FOB USA).
point switch, and output drivers. The four
output channels have redundant outputs
for test or fanning purposes. When four
output channels have been deselected, the
output drivers power down to reduce
power consumption by 165mW—a unique
power-saving feature. Power consumption
with four output channels enabled is only
257mW. A fully differential architecture
ensures minimum crosstalk, signal skew,
and jitter accumulation. The MAX3640
exhibits only 2.8psRMS random output
jitter and 42ps deterministic output jitter.
The MAX3640 is available in a 48-pin
TQFP package and operates from a 3.3V
supply over a temperature range of 0°C to
+85°C. Prices start at $9.99 (1000–up,
FOB USA). An evaluation kit is available.
First SOT23 dualtemperature
comparators need
no external
The MAX6505–MAX6508 family of dual
thermal comparators is the latest addition
to an industry-leading line of temperature
switches. These ICs are the smallest and
lowest power dual-temperature switches
Combining two temperature comparators
on a single chip, each device simplifies
the incorporation of reliability-enhancing
temperature-control, protection, and
warning functions in a system. Because
temperature thresholds are preset at the
factory, no external components are
required to set the temperature trip points.
Each device asserts an ALARM when the
temperature exceeds the factory-set trip
temperature. The MAX6505/MAX6506
also have a WARN output. Trip temperature for the WARN output is pin selected
by the user to equal 5°C, 10°C, 20°C, or
30°C below the ALARM trip temperature.
The MAX6507/MAX6508 also have two
logic outputs, OK and OVER. OK
indicates whether the device temperature
falls within the range bounded by the
factory-set upper and lower trip temperatures. OVER indicates when temperature
exceeds the upper trip temperature.
MAX6505/MAX6507 outputs are open
drain, and MAX6506/MAX6508 outputs
are push-pull. All four devices come in a
6-pin SOT23 package and operate from a
+2.5V to +5.5V supply. Prices start at
$0.79 (1000–up, FOB USA).
3.3V quad-port
bypass IC operates
at 2.125Gbps/
Tiny chip-scale
power amplifier for
Bluetooth Class I
The MAX3752 quad-port bypass IC
consists of four serially connected portbypass circuits (PBCs) and a repeater that
provides clock and data recovery (CDR). It
operates with a single 3.0V to 3.6V supply
and is designed for use in the Fibre
Channel Arbitrated Loop topology.
The MAX2240 is the first power amplifier
(PA) designed specifically for Bluetooth
radios and is also the smallest such PA
available for Bluetooth Class I radios. The
2.4GHz, 100mW device comes in a
0.5mm pitch, 9-pin (3x3 array) ultra-chipscale package (UCSP)—the latest technology in RFIC packaging. It occupies
only 16% of the space required by the
8-pin MSOP package of competitive
devices. Its +20dBm output power allows
the user to extend radio link range to 100
meters, a capability ideal for notebook
PCs, cellular phones, and other Bluetooth
devices operating in changing environments.
The port-bypass circuits allow connection
to as many as four Fibre Channel L-ports,
each of which can be enabled or bypassed
through the PBC-select inputs. Additional
quad PBCs can be cascaded in applications
that require more than four L-ports. To
minimize the external parts count, all
signal inputs and outputs have internal
termination resistors compatible with 75Ω
transmission lines.
The MAX3752 complies with the Fibre
Channel jitter-tolerance requirements and
is capable of recovering data signals with
up to 0.7 unit intervals (UIs) of highfrequency jitter. When not needed, the
repeater can be disabled to reduce power
consumption. Frequency-lock indication is
provided by a fully integrated phaselocked loop (PLL), which does not need an
external reference clock.
The MAX3752 is optimized for 2.125Gbps
or 1.063Gbps operation. It is packaged in a
48-pin TQFP-EP (with exposed paddle),
and prices start at $11.00 (1000–up, FOB
Miniature VCOs
suit 45MHz
to 650MHz
The MAX2605–MAX2609 family of
miniature VCOs is designed for IF and RF
applications such as cellular phones,
wireless LANs, cordless phones, and other
equipment requiring a fixed oscillator
frequency between 45MHz and 650MHz.
The MAX2240 is also suitable for use in
HomeRF, 802.11 FHSS, and other
2.4GHz proprietary ISM-band radio applications. Its digital power-control function,
a unique feature in the marketplace,
allows the user to reduce transmit power
in four 6dB steps, down to +4dBm or less,
as required in Bluetooth Power Class I
specifications. The MAX2240 features an
integrated 50Ω input match that further
reduces the external component count and
required board space.
Dual-band SiGe
LNA/mixer ICs
offer adjustable
gain and high
The MAX2320–MAX2324 and MAX2326/
MAX2327 SiGe ICs comprise high-performance receiver front ends that set new
industry standards for low noise and high
linearity at low supply current. Features
include an LO frequency doubler
(MAX2321), LO frequency divider
(MAX2326), LO output buffers, adjustable
gain settings for the dual low-noise amplifiers (LNAs), and a low-current paging
mode that extends the handset standby
All devices operate with a single 2.7V to
3.6V supply, with a 0.1µ A standby
current. One operates at cellular frequencies, one at PCS frequencies, and four at
both cellular and PCS frequencies (see the
Product Selector Guide available from
Maxim). To minimize intermodulation
and crossmodulation in the presence of
large interfering signals, each device
includes an LNA with high input thirdorder intercept point (IIP3). The LNA is
bypassed in low-gain mode to provide a
higher cascaded IIP3 at lower current.
Each device provides a low-current, highgain mode for paging.
The MAX2240 operates on a single 2.7V
to 5.0V supply and draws only 105mA. A
1µA low-power shutdown mode helps to
reduce power consumption and extend
battery life. Prices start at $1.75 (1000–up,
FOB USA). A fully assembled evaluation
kit (MAX2240EVKIT) is available to help
reduce design time.
Internal CDMA mixers for the cellular
and PCS bands have high linearity, low
noise, and differential IF outputs. The FM
mixers, designed for lower current, have
single-ended outputs. All devices come in
a 20-pin TSSOP-EP (with exposed
paddle), specified for the extended-industrial temperature range (-40°C to +85°C).
Prices start at $3.00 (1000–up, FOB
Unlike discrete designs, which require up
to 15 components and long design times,
the MAX2605–MAX2609 are simple to
use and require only one external inductor
to set the oscillation frequency.
varactor’s tuning range is factory tested to
guarantee startup and proper operation
over temperature. Depending on the
operating frequency, these devices draw
between 2.1mA and 3.7mA of supply
current and achieve between -112dBc/Hz
and -107dBc/Hz phase noise (at 100kHz
offset from the carrier). Prices start at
$0.83 (1000–up, FOB USA).
MAX2605–MAX2609 VCOs integrate
varactors, core transistors, bias circuitry,
coupling capacitors, and a differential
output buffer in a miniature 6-pin SOT23
package, offering ease of use, a small
footprint, and low cost. The internal
1.8GHz to 2.5GHz
receivers simplify
wideband WLL
MAX2700/MAX2701 ICs are the first
available direct-conversion receivers
designed for wideband wireless local-loop
(WLL) systems. (This architecture allows
single-chip integration by eliminating the
IF SAW filter, RF downconverter, and IF
VCO components.) Direct conversion
(zero-IF) architectures reduce cost and
component count by eliminating one or
two of the frequency downconversions
typically found in today’s superheterodyne systems. They also improve system
reliability and manufacturing yield—two
key factors in lowering the cost of WLL
subscriber equipment. When combined
with MAX2720/MAX2721 direct I/Q
transmitters, they form a complete chipset
for WLL systems operating in the
1.8GHz, 1.9GHz, 2.1GHz, 2.3GHz, and
2.4GHz frequency bands, with channel
bandwidths exceeding 50MHz.
The MAX2700 is optimized for operation
in the 1.8GHz to 2.1GHz band, and the
MAX2701 is optimized for the 2.1GHz to
2.5GHz band. Both receiver ICs include
three main blocks: LNA, quadrature
downconverter, and baseband variable
gain amplifiers (VGAs). The LNA
provides 17dB gain, 2.3dB noise figure,
and +4dBm input IP3 at 2.4GHz. (High
input IP3 helps minimize cross modulation and gain compression due to highlevel RF interference.)
The quadrature downconverter consists of
two highly linear double-balanced mixers
driven by an external LO, a selectable LO
doubler, and a wideband LO quadrature
generator. The double-balanced mixers
are optimized for high input IP2, IP3, and
minimum added noise. The MAX2701
provides a mixer input IP2 of +38dBm
and an IP3 of +6dBm. The high input IP2
helps to minimize desensitization in the
receiver, caused by in-band AMmodulated high-level interferers.
The two baseband VGAs in each channel
provide 80dB of total maximum gain and
>60dB of gain control. External lowpass
filters connected in the baseband interstages provide the necessary channel
selectivity. Integrated into the
MAX2700/MAX2701 is an amplitude/
gain-correction loop, which guarantees the
match between I and Q channel amplitudes to be <0.7dB.
The MAX2700/MAX2701 are also
suitable for 2-way MMDS and 2.4GHz
ISM wideband systems. Both ICs are
available in a small 48-pin TQFP package
with exposed paddle, which optimizes
high-frequency performance. Prices start
at $4.95 (1000–up, FOB USA). A fully
assembled evaluation kit (MAX2700/
MAX2701EVKIT) is available to help
reduce design time.
GPS receiver IC
provides <0.5
meter accuracy
and 5ns timing
and good immunity to in-channel jammers.
Including all filter losses, the total receiver
gain is >100dB, with >50dB of automatic
gain-control range. Requiring minimal
external components, the MAX2740 with
its unique frequency plan is suitable for
use in joint GPS/GLONASS receivers.
The MAX2740 GPS receiver IC offers the
best timing resolution (5ns) and the most
competitive positional accuracy (<0.5
meter) in the industry. Typical GPS
receivers offer 300ns timing resolution and
positional accuracy >1 meter.
An RF-only multichip module and several
complete modules that incorporate the
MAX2740 are available through Parthus,
Ltd. (See MAX2740
devices come in a small 48-pin TQFP
package with exposed paddle, which
provides optimum high-frequency performance. Prices start at $13.90 (100–up,
The MAX2740 is a complete GPS/
GLONASS receiver from antenna to
digitizer input. It allows the use of a multilevel digitizer for high receiver sensitivity
Tiny, 900MHz SiGe
LNA offers variable
IP3 and gain-step
The 900MHz MAX2642/MAX2643 are
the world’s smallest SiGe LNAs. The first
available in a tiny 6-pin SC70 package
measuring only 2.0mmx2.1mm, they also
pack the most features in a 6-pin package:
variable IP3, gain-step control, and lowpower shutdown. Variable IP3 and gainstep control allow users to maximize the
receiver linearity without wasting supply
current. At 5mA, the NF and IP3 for these
devices (1.3dB, 0dBm) outperforms the
HP MGA-87563 GaAs PHEMT (1.9dB,
-7dBm) and the Infineon BGA427 Si BJT
(2dB, -5dBm).
MAX2642/MAX2643 LNAs provide
17dB gain, 1.3dB noise figure, and 0dBm
input IP3, using only 5mA of current. By
varying the resistor connected to the BIAS
pin, you can adjust the input IP3 from
-11dBm to +1dBm, while the supply
current varies from 2mA to 6mA. This
capability allows users to dial in the
required IP3 without wasting supply
current. The MAX2642’s 13dB gain-step
control helps to extend the LNA’s dynamic
range. MAX2643 gain remains fixed. The
MAX2643 shuts down by logic control,
and the MAX2642 shuts down by disconnecting the BIAS pin. Both amplifiers
incorporate on-chip output matching,
which reduces the number of external
The MAX2642/MAX2643 are ideal for
cellular and cordless phone applications,
PMR/SMR, 868MHz/900MHz ISM, and
general-purpose buffers or driver amplifiers.
Both devices operate from a single 2.7V to
5.5V supply. Prices start at $0.89 (1000–up,
FOB USA). A fully assembled evaluation
kit (MAX2642/MAX2643EVKIT) is available to help reduce design time.
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