NEWS BRIEFS IN-DEPTH ARTICLES
Volume Thirty-Six
NEWS BRIEFS
IN-DEPTH ARTICLES
Maxim reports record revenues and earnings for its fourth quarter
and its fiscal year
2
ADC captures 1Gsps
3
How to select the right CMOS analog switch
7
How to simplify the interface between microcontroller and temperature sensor
NEW PRODUCTS
12
Data Converters
• High-performance 8-bit ADC with track/hold converts at 600Msps
• 12- and 14-bit DACs with 1LSB INL eliminate power-up glitch
(MAX106)
(MAX5170–5177)
16
16
(MAX6576/6577)
16
(MAX4194–4197)
(MAX4174/4175/
4274/4275, 4281/2/4)
17
(MAX4370)
17
(MAX6012/21/25/30/
41/45/50)
18
(MAX4311/12/14/15)
(MAX4533)
(MAX4548/4549)
(MAX4558/59/60)
18
18
19
19
(MAX7400/03/04/07)
19
(MAX618)
(MAX1623)
(MAX1644)
(MAX1666)
(MAX1667)
(MAX1687/1688)
(MAX1719/1720/1721)
(MAX1749)
20
20
21
21
21
20
22
19
(MAX3110E/3111E)
(MAX3140)
(MAX3180E–3183E)
(MAX3483E/85E/86E/
88E/90E/91E)
23
22
22
(MAX2235)
(MAX2472/2473)
23
23
Temperature Sensors
• SOT temperature sensors have single-wire outputs
Amplifiers
• 2.7V rail-to-rail instrumentation amplifiers achieve 115dB CMRR
• Rail-to-rail SOT23 op amps include gain-setting resistors
17
Hot Swap Solutions
• Hot swap controller speeds start-up and improves fault response
Voltage References
• Precision, low-dropout voltage references offer 15ppm/°C stability
Multiplexers/Switches
•
•
•
•
4/8-channel video mux amps operate from single +5V supply
Rail-to-rail, quad SPDT analog switch has ±40V fault protection
Triple audio/video crosspoint switches have serial control
Low-voltage analog mux/switches have ±15kV ESD protection
Filters
• Lowpass switched-capacitor filters have 8th-order elliptic response
Power-Management ICs
•
•
•
•
•
•
•
•
28V PWM step-up DC-DC converter delivers high voltage and current
Synchronous, switch-mode buck regulator has 3A internal switches
Small, high-frequency step-down converter has internal switches
Li+ cell protector is 0.5% accurate
Single chip charges Li+ cells
Boost converters drive 2A Tx burst with 6x-lower battery current
Switched-capacitor voltage inverters offer shutdown
Single chip drives pager-vibrator motor
Interface ICs
•
•
•
•
Integrated RS-232/UART saves space, power, and I/O pins
IC combines UART and RS-485 transceiver
RS-232 receivers in SOT packages have ±15kV ESD protection
3V RS-485/RS-422 transceivers feature ±15kV ESD protection
22
Wireless ICs
• 900MHz, 1W silicon PA reduces output noise and spectral splatter
• Wideband buffer amps in SOT23-6
News Briefs
MAXIM REPORTS RECORD REVENUES AND EARNINGS FOR ITS FOURTH
QUARTER AND ITS FISCAL YEAR
Maxim Integrated Products, Inc., (MXIM) reported record net revenues of $159.5 million for the fourth quarter of
fiscal 1999 ending June 26, 1999, compared to $155.2 million for the same quarter in fiscal 1998. Net income increased
to a record $52.6 million in Q499, compared to $49.2 million for the fourth quarter of fiscal 1998. Diluted earnings per
share were $0.34 for Q499, compared to $0.33 for the same period a year ago.
For the fiscal year ending June 26, 1999, Maxim reported net revenues of $607.0 million, an 8.3% increase
over the $560.2 million reported for fiscal 1998. Net income increased to $196.1 million in fiscal 1999, compared to
$178.1 million in fiscal 1998. Diluted earnings per share increased 9.3% to $1.29 in fiscal 1999 from $1.18 in the prior
fiscal year.
During the quarter, the Company increased cash and short-term investments by $49.9 million after paying
$43.4 million for 775,000 shares of its common stock and $14.2 million for capital equipment. For the year, the
Company increased cash and short-term investments by $191.8 million after paying $113.9 million for 2,915,000
shares of its common stock and $38.7 million for capital equipment.
Gross margin for the fourth quarter increased to 69.7%, compared to 69.1% in Q399. During the quarter, the
Company recorded a writedown of equipment of $2.7 million and increased inventory reserves by $2.5 million. The
Company also recorded a charge to selling, general and administrative expenses of $1.0 million related to technology
licensing matters.
Bookings on the Company were approximately $198 million in Q499, a 16% increase over the Q399 level of
$171 million. Turns orders received in Q499 were $81 million, a 17% increase over Q399 levels (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).
End-market bookings increased 9% over Q399 levels (end-market bookings are end-user customer bookings
received by both Maxim and the Company’s distributors during the quarter). This increase is attributable mainly to
strength in the U.S. OEM, U.S. distribution, and Japanese sales channels. Bookings on Maxim by U.S. distributors were
$49.3 million and exceeded customer bookings on those distributors by $11.5 million. Bookings for the Pacific Rim
decreased in Q4, while bookings in Europe were flat with the prior quarter.
There was continued strength in the notebook and communications end markets during the quarter. In addition,
there was a considerable increase in demand for the Company’s products that target its more traditional broad-based
industrial end markets.
Fourth quarter ending backlog shippable within the next 12 months was approximately $176 million, including
$144 million requested for shipment in the first quarter of fiscal 2000. Last quarter, the Company reported third quarter
ending backlog shippable within the next 12 months of approximately $148 million, including $120 million requested for
shipment in Q499. Order cancellations during Q499 were approximately $13 million, compared to $10 million in Q399.
Jack Gifford, Chairman, President, and Chief Executive Officer, commented on the quarter: “Q4 was a record
bookings quarter for Maxim. We saw particularly strong growth in U.S. OEM bookings. Turns orders continued to
constitute approximately 40% of total bookings, extending the trend of near-term ordering. As we mentioned last quarter,
we believe that bookings will adjust to our predicted growth levels of 5% to 7% per quarter, and that as inventories
recover from previously depleted levels, turns will constitute a smaller percentage of total orders.
“While our fourth quarter revenues increased 8.4% over last quarter, our profits increased 10.3% because of
greater manufacturing efficiencies, resulting in higher gross margins. I think it’s impressive that during the 1999 fiscal
year, Maxim was able to generate over $190 million in cash, buy back 2.9 million shares of its stock, and spend less than
$40 million on capital equipment, given that we are not a software company!”
Gifford continued: “Although two of our six business units significantly missed their fourth quarter product introduction plans, causing us to miss by approximately 5 percent our goal of introducing over 300 products in the product
year ending in July, we executed well overall both for the quarter and the year, significantly surpassing last year’s
product introduction level. I am encouraged by the excitement with which engineers are greeting many of our new
product offerings, particularly in the communications area.”
ADC Captures
1Gsps
small geometry, and precision laser-trimmed nickelchrome (NiCr) thin-film resistors), additional credit goes
to the MAX104’s design team for creating an efficient
and effective ADC architecture.
Most high-speed ADCs that sample more than several
hundred megahertz have input bandwidths that are limited
to no more than their maximum sampling frequency to
improve noise performance. One example is the signal-tonoise ratio (SNR). This limited input bandwidth may rule
out use in applications where bandwidths of interest in the
input spectrum are higher, and an undersampling approach
is needed. Also, if the input signal is changing rapidly
during conversion, the effective number of bits (ENOB)
and SNR will be reduced. The MAX104’s on-chip 2.2GHz
full-power-bandwidth T/H amplifier (Figure 2) increases
dynamic performance significantly and supports more
precise capture of fast analog data at extremely high
conversion rates.
[This article appeared in the March 1999 Microwaves and RF magazine]
The MAX104 processes analog input bandwidths that
exceed 2.2GHz with 8-bit resolution. It sets a new
standard for performance in high-frequency, highbandwidth digital communications receivers, digital
oscilloscopes, and high-speed data-acquisition systems.
The MAX104 is a fast silicon monolithic analog-todigital converter (ADC) that integrates a high-bandwidth
track/hold (T/H) amplifier (Figure 1) with a high-speed
quantizer that supports accurate digitizing of wideband
analog input signals from DC to 2.2GHz. It is based on
Maxim’s GST-2 Giga-Speed silicon-bipolar process technology. This high-speed, self-aligned double-polysilicon
process has been developed for high-density, high-performance circuits. It employs many of the features, such as
trench isolation, that are incorporated in Maxim’s lower
performance GST-1 process.
Bandgap reference
The MAX104 features an on-board +2.5V precision
bandgap reference, which can be activated by connecting
the bandgap reference’s output contact (REFOUT) to the
in-phase input (REFIN) of the internal reference
amplifier. The negative input of this amplifier is internally tied to the reference ground (GNDR).
Although many of the outstanding performance parameters of the MAX104 are possible with the integratedcircuit process (such as a transition frequency of 27GHz
for NPN transistors, a three-metal interconnect system,
REF REF
OUT IN
BANDGAP
REFERENCE
REFERENCE
AMPLIFIER
+2.5V
DIFFERENTIAL
PECL OUTPUTS
MAX104
VOSADJ
GNDR
OVERRANGE
BIT
BIAS CURRENTS
GNDI
OR
2
50Ω
T/H AMPLIFIER
VIN+
8-BIT
FLASH ADC
VIN-
AUXILIARY
DATA PORT
2
16
50Ω
CLK+
LOGIC
CLOCK
DRIVER
50Ω
CLK-
RSTIN+
RSTIN-
T/H
CLOCK
DRIVER
RESET INPUT
DUAL LATCH
ADC
CLOCK
DRIVER
RESET
PIPELINE
PRIMARY
DATA PORT
16
DATA
READY CLOCK
2
P0–P7
DREADY
DEMUX
CLOCK
DRIVER
CLKCOM
50Ω
A0–A7
16
DELAYED
RESET
DEMUXEN
DEMUX
CLOCK
GENERATOR
DEMUX
RESET OUTPUT
RSTOUT
2
DIVSELECT
Figure 1. This simplified block diagram shows how the MAX104 integrates a high-bandwidth T/H amplifier with a high-speed quantizer.
3
For a zero-scale digital output code, the negative input
(VIN-) must be 250mV above the positive input (VIN+).
The high-performance differential T/H amplifier enables
the MAX104 to be used in single-ended input configurations without any degradation in dynamic performance.
For a typical single-ended configuration, the analog input
signal is coupled to the T/H amplifier stage at the inphase input pad (VIN+), while the inverted phase input
(VIN-) pad is referenced to ground. Single-ended
operation supports an input amplitude of 500mV peak-topeak, centered at approximately 0V. For minimizing
reflections and improving performance, the MAX104
inputs feature impedance-matched, on-chip, lasertrimmed 50Ω NiCr termination resistors.
0
AMPLITUDE (dB)
-1
-2
-3
-4
FULL-POWER BANDWIDTH = 2.2GHz
-5
500
1500 2500
FREQUENCY (MHz)
Figure 2. The MAX104’s full-power bandwidth is shown as a
function of input amplitude.
Demonstrating almost identical dynamic performance at
analog input frequencies of 125MHz (Figure 3),
250MHz, 500MHz (Figure 4), and 1GHz (Figure 5) with
a sampling rate of 1Gsps for differential and single-ended
analog input operation, the MAX104 solves one of the
most perplexing problems in high-speed ADC applications—the need for costly, space-consuming, singleended-to-differential signal-conversion circuitry. Now,
applications requiring single-ended signal sources can
just feed this signal into the VIN+ pin and terminate the
VIN- pin through a 50Ω resistor connected to ground.
The REFOUT port can provide a current of up to 2.5mA
for external devices. This is enough drive for two
MAX104s configured for interleaved operation (to
achieve a sampling rate of 2 gigasamples per second, or
2Gsps). Since the bandgap reference source is internally
compensated, external bypass components are not needed
with REFOUT connections.
To overdrive the internal reference, an external precision
reference can be connected to the REFIN pin with
REFOUT left floating. The external reference may then
be used to adjust the full-scale range of the MAX104.
Similar to its analog input structure, the MAX104 features
clock inputs designed for either single-ended or differential
operation with very flexible input-drive requirements. Each
clock input is terminated with an on-chip, laser-trimmed,
50Ω precision NiCr resistor to the clock-termination return.
This termination may be connected anywhere between
ground and -2V for compatibility with standard emittercoupled-logic (ECL) drive levels.
The MAX104’s T/H amplifier input circuit design
reduces the input signal requirement and supports a fullscale signal input range of 500mV peak-to-peak.
Obtaining a full-scale digital output with a differential
input requires 250mV applied between the positive
(VIN+) and the negative input (VIN-) pins. Midscale
digital output codes occur at an input of 0V.
(fIN = 494.5068MHz, RECORD LENGTH 8192)
(fIN = 125.8545MHz, RECORD LENGTN 8192)
0
0
ENOB = 7.75 BITS
SNR = 47.4dB
THD = -66.2dB
SFDR = 70.3dB
fSAMPLE = 1GHz
-25.6
AMPLITUDE (dB)
AMPLITUDE (dB)
-25.6
ENOB = 7.51 BITS
SNR = 46.8dB
THD = -51.9dB
SFDR = 52.1dB
fSAMPLE = 1GHz
-51.2
-76.8
-51.2
-76.8
-102.4
-102.4
-128.0
-128.0
0
0
100
200
300
400
500
100
200
300
400
500
ANALOG INPUT FREQUENCY (MHz)
ANALOG INPUT FREQUENCY (MHz)
Figure 3. This fast Fourier transform (FFT) demonstrates the oversampled performance of the MAX104 at a sampling rate of
1Gsps and an analog input frequency of 125MHz.
Figure 4. This FFT was taken at a Nyquist frequency of 500MHz
and a sampling rate of 1Gsps.
4
presented in dual 8-bit format with two consecutive
samples in the primary and auxiliary output ports on the
rising edge of the data-ready clock. The DIV1 nondemultiplexed (nondemux) mode supports operation of the
MAX104 at sampling speeds up to 500 megasamples per
second (Msps). In this mode, the internal demux is
disabled and the sampled data are presented to the
primary output port only. To consume less power, the
auxiliary port can be shut down by two separate inputs
(AUXEN1 and AUXEN2). To save additional power, the
external 50Ω termination resistors connected to the logic
PECL power supply (VCCO at -2V) can be removed from
all auxiliary output ports.
(fIN = 1005.0049MHz, RECORD LENGTH 8192)
0
ENOB = 7.51 BITS
SNR = 46.3dB
THD = -52.8dB
SFDR = 53.7dB
fSAMPLE = 1GHz
AMPLITUDE (dB)
-25.6
-51.2
-76.8
-102.4
-128.0
0
100
200
300
400
500
ANALOG INPUT FREQUENCY (MHz)
Figure 5. This FFT was measured with the MAX104 undersampling an
analog input frequency of 1GHz at a sampling rate of 1Gsps.
In a special decimated, demuxed output mode (DIV4), the
MAX104 discards every other input sample and outputs
data at one quarter of the input sampling rate. This mode
is particularly useful for system debugging using the
resulting slower output data rates. With an input clock of
1GHz, the effective output data rate will be reduced to
250MHz in this mode.
The clock inputs are internally buffered with an amplifier
to ensure proper operation of the ADC even with smallamplitude sine-wave sources. The MAX104 was designed
for single-ended operation, maintaining superior dynamic
performance when using low-phase-noise sine-wave
clock input signals with as little as 100mV amplitude.
Along with the on-chip demux, the MAX104 provides
internal demux reset circuitry that enables multiple ADCs
to be synchronized for proper interleaving operation. In
addition, the reset signal appears as an external demux
reset output for synchronizing external demuxes.
To obtain the lowest jitter clock drive, a low-phase-noise
sine-wave source can be AC- or DC-coupled into a single
clock input. The MAX104 can accommodate clock
amplitudes up to 1V (2V peak-to-peak) with the clocktermination return connected to ground. The dynamic
performance of the ADC is essentially unaffected by
clock signal amplitudes from 100mV to 1V.
Furthermore, the MAX104 provides latched, differential
PECL outputs, which make the ADC ideal for driving
controlled low-impedance lines. The PECL outputs can
be powered from +3V to +5.25V DC supply voltages.
PECL outputs on the MAX104 are typically terminated
with a parallel 50Ω termination resistor into V TT =
VCCO - 2V (the PECL termination voltage).
The ADC can be driven from a standard differential ECL
clock source by simply setting the clock-termination
voltage to -2V. To maintain the best performance, a veryhigh-speed differential ECL driver should be used.
Primary port outputs are labeled P0–P7 (LSB to MSB),
while the auxiliary ports are labeled A0–A7. Outputs
DREADY+ and DREADY- are data-ready true and
complementary outputs, supplying the data clock.
Clock inputs CLK+ and CLK- may also be driven with
positive referenced ECL (PECL) logic levels if the clock
inputs are AC coupled. A single-ended ECL drive can
also be used if the undriven clock input is connected to
the ECL VTT voltage (nominally -1.3V).
These signal lines are used to latch the output data from
the primary to the auxiliary output ports, as well as
supplying a synchronous clock for downstream digital
circuitry, such as demuxes or high-speed memory
devices. Data changes are triggered on the rising edge of
the DREADY clock.
Another useful feature of the MAX104 may be its internal
output demultiplexer (demux) circuitry. This circuitry
provides three different modes of operation. The demux
operation is controlled by two transistor-transistor-logic
(TTL)/complementary-metal-oxide-semiconductor
(CMOS)-compatible digital inputs: DEMUXEN, which
activates or deactivates the internal demux, and
DIVSELECT, which selects one of three demux modes
(DIV1, DIV2, or DIV4).
Outputs OR+ and OR- are overrange true and complementary outputs. Outputs RSTOUT+ and RSTOUT- are
the reset-out true and complementary outputs provided to
reset downstream circuitry.
The DIV2 (demux) mode reduces the output data rate to
one-half the sample clock rate. The demuxed outputs are
The MAX104 is supplied in a 192-contact enhanced-superball-grid-array (ESBGA) package from Amkor/Anam
5
Nyquist frequency (e.g., operating at 1GHz) make the
MAX104 the converter of choice for oversampled as well
as undersampled 8-bit digital communications applications. For instance, the MAX104 delivers a 47.4dB SNR
and 68.9dB SFDR at an analog input frequency of
125MHz. The two-tone performance is an impressive
-57.7dB at the same test frequency.
(Chandler, AZ) that measures 25mm x 25mm. The
MAX104 provides an on-board 1:2 demux function,
slowing data rates to 500Mbps supplied on two ports. The
package features 50Ω microstrip interconnects from the
solder balls to the bond wires, which support high
input/output (I/O) operating frequencies. In addition, the
package enables a large number of solder balls to be
dedicated to power supplies and ground. With a thickness of
only 1.4mm, this 1.27mm pitch ESBGA package saves
circuit-board space while providing excellent thermal
performance. In many applications, the MAX104 can be
used without a heat sink.
Another ideal application is in DAQ instruments and
systems. These are systems that are designed to sample,
analyze, and display signal waveforms detected at various
nodes within a circuit under analysis (e.g., high-speed,
multichannel digital oscilloscopes). ADCs are used in the
front-end circuitry of digital sampling oscilloscopes
(DSOs). Often, multiple converters are time interleaved to
increase an effective sampling frequency. Maxim’s new
600Msps/1.5Gsps converter, the MAX106, provides
designers with the options of lower and even higher
sampling speeds.
The MAX104 is ideal for many applications where high
sampling rates are required to either capture an instantaneous value from a fast-moving signal, such as in a highspeed data acquisition (DAQ) application, or to digitize a
complex high-frequency, high-bandwidth signal. One
example of this is in wideband digital receivers for digital
base stations. In this case, signal bandwidths that exceed
300MHz are allowed to pass through the receiver intermediate-frequency (IF) stages to the demodulator. At this
point, the information bandwidth may be filtered and
amplified before being presented to the ADC front end.
This approach, known as block or direct downconversion,
requires that the input bandwidth of the ADC be sufficiently
flat to prevent distortions and nonlinearities in the resulting
digital representation. The high-speed data stream thus
created is then presented to a digital demodulator which
separates the individual channels and extracts the modulated
information.
Important data-converter specifications in DAQ applications include an analog signal input bandwidth, gain
flatness, ENOB performance, and low occurrence of
metastable states. A differential comparator design and its
decoding circuitry reduce out-of-sequence code errors,
such as thermometer bubbles or sparkle codes, and
provide excellent metastable performance of less than one
error per 1016 clock cycles. Unlike other ADCs, which
may have errors that result in false full-scale or zero-scale
outputs, the MAX104 keeps its error magnitude to no
more than 1LSB.
Furthermore, this fast ADC accomplishes outstanding
numbers for integral-nonlinearity (INL) and differentialnonlinearity (DNL) parameters, ensuring monotonic
operation. After trimming, the MAX104 displays parameters as low as ±0.25LSB (Figures 6, 7).
Applying the ADC
The exceptional SNR and spurious-free dynamic-range
(SFDR) performance of the MAX104 at input frequencies
below (e.g., at 125MHz and 250MHz) and well above the
INTEGRAL NONLINEARITY
vs. OUTPUT CODE
(LOW-FREQUENCY SERVO LOOP DATA)
0.3
MAX104toc25
0.4
0.4
0.3
0.2
0.2
0.1
0.1
DNL (LSB)
INL (LSB)
0.5
MAX104toc24
0.5
DIFFERENTIAL NONLINEARITY
vs. OUTPUT CODE
(LOW-FREQUENCY SERVO LOOP DATA)
0
-0.1
0
-0.1
-0.2
-0.2
-0.3
-0.3
-0.4
-0.4
-0.5
-0.5
0
32
64
96
128 160 192 224
256
0
OUTPUT CODE
32
64
96
128 160 192 224
256
OUTPUT CODE
Figure 6. The MAX104’s typical integral nonlinearity
Figure 7. The MAX104’s typical differential nonlinearity
6
How to select the
right CMOS
analog switch
Taking the P- and N-channel on-resistances (RON) in
parallel (product over sum) for each level of VIN yields a
composite on-resistance characteristic for the parallel
structure (Figure 2). This plot of RON vs. VIN can be
described as linear if you exclude the effects of temperature, power-supply voltage, and R ON variation with
analog input voltage. Be aware, however, that these
effects represent disadvantages, and that minimizing them
is often the primary purpose of new products.
Integrated analog switches often form an interface
between a digital controller and analog signals. This
article gives the theoretical background for analog
switches and describes some common applications for
standard types. It also discusses the special features of
calibration multiplexers (cal-muxes), fault-protected
switches, and force-sense switches.
The first analog switches operated on ±20V supply
voltages and had several hundred ohms of R ON. The
latest products (Maxim’s MAX4601, for instance)
achieve 2.5Ω max R ON with a much lower supply
voltage. Supply voltage has a significant effect on RON
(Figure 3). The MAX4601 specifies signal and supply
voltages from +4.5V to +36V or from ±4.5V to ±20V. As
you can see, RON increases for lower supply voltages.
The max RON is about 8Ω at +5V, 3Ω at +12V, and only
2.5Ω at +24V. Some new analog switches specify lowvoltage operation for supplies as low as +2V. Figure 4
In recent years, integrated analog switches have offered
better switching characteristics, lower supply voltages,
and smaller packages. Because so many performance
options and special functions are now available, the wellinformed product designer has a good chance of finding
the ideal part for a particular application.
Although CMOS analog switches are often taken for
granted because they are easy to use, don’t overlook their
ability to solve certain engineering problems. Conventional
analog switches such as the early CD4066 or MAX4066 are
now offered by many manufacturers; their basic structure is
shown in Figure 1.
ON-RESISTANCE vs. VIN
250
P-CHANNEL
RON (Ω)
200
150
100
Connecting an N-channel MOSFET in parallel with a
P-channel MOSFET allows signals to pass in either
direction with equal ease. Because the switch has no
preferred direction for current flow, it has no preferred
input or output. The two MOSFETs are switched on and
off by internal inverting and noninverting amplifiers.
These amplifiers level-shift the digital input signal as required, according to whether the signal is CMOS- or
TTL-logic compatible, and whether the analog supply
voltage is single or dual.
N-CHANNEL
50
0
-15
-10
-5
0
5
10
15
VIN (V)
Figure 2. The N-channel and P-channel on-resistances of Figure 1
form a low-valued composite on-resistance.
MAX4601/MAX4602/MAX4603
ON-RESISTANCE vs. VCOM
(SINGLE SUPPLY)
10
9
V+ = 5V
8
7
IN
BODY
S
OUT
D
G
LOGIC 1 = ON
N-CHANNEL
RON (Ω)
V-
V+
BODY
S
6
5
V+ = 12V
4
V+ = 24V
3
D
2
G
1
0
0
2
4
6
8 10 12 14 16 18 20 22 24
VCOM (V)
Figure 1. The internal construction of a typical analog switch
features parallel N- and P-channel MOSFETs.
Figure 3. Higher supply voltage causes lower on-resistance.
7
compares the performance of the new Maxim switches with
older switch types for +5V supplies.
charge injection caused by higher levels of capacitive
gate current. A certain amount of charge is added to or
subtracted from the analog channel with every on or off
transition of the switch (Figure 5). For switches connected to high-impedance outputs, this action can cause
significant changes in the expected output signal. A small
parasitic capacitor (CL) (and no other load) adds a variation
of ∆V OUT , so charge injection can be calculated as
Q = ∆VOUT(CL).
Many high-performance analog systems still rely on
higher level bipolar supplies such as ±15V or ±12V. The
interface to these voltages requires an additional supply
pin. That pin connects to the system logic voltage, which
is usually 5V or 3.3V. Having the input logic signals
referenced to the actual logic levels increases the noise
margin and prevents excessive power dissipation.
A track/hold amplifier, which maintains a constant analog
output during conversion by an analog-to-digital converter
(ADC), offers a good example (Figure 6). Closing S1
charges the small buffer capacitor (C) to the input voltage
(VS). The value of C is only a few picofarads, and VS
Signal handling
A second look at Figure 3 shows the value of RON vs.
signal voltage. These curves fall within the specified
supply range, because analog switches can only handle
analog signal levels between the supply voltages. Underor overvoltage input signals can permanently damage an
unprotected switch by producing uncontrolled currents
through internal diode networks. Normally, these diodes
protect the switch against short-duration electrostatic
discharge (ESD) as high as ±2kV.
ON-RESISTANCE vs. VCOM
160
V+ = +5V
140
DG411
rDS(ON) (Ω)
120
RON for a typical CMOS analog switch causes a linear
reduction of signal voltage that is proportional to current
passing through the switch. This might not be a disadvantage for modest levels of current, or if the design accounts
for RON effects. If, however, you accept a certain level of
RON, then channel matching and RON flatness can become
significant. Channel matching describes the variation of
RON for the channels of one device, and RON flatness
describes the variation of RON vs. signal range for a single
channel. Typical values for these parameters are 2Ω to 5Ω;
very low-RON switches (i.e., the MAX4601) have only
0.5Ω max. The smaller the ratio of matching/RON or
flatness/RON, the more accurate the switch.
100
74HC4066
80
60
40
20
MAX4614
0
0
1
2
3
4
5
VCOM (V)
Figure 4. At +5V supply voltage, later generation analog switches
have lower on-resistance.
V+
V+
RGEN
Charge-injection effects
NO
COM
VOUT
CL
V GEN
Low on-resistance is not necessary in all applications.
Lower RON requires greater chip area, and the result is a
greater input capacitance whose charge and discharge
currents dissipate more power in every switching cycle.
Based on the time constant t = RC, this charging time
depends on load resistance (R) and capacitance (C).
GND
IN
VIN
∆VOUT
OUT
Maxim offers both types, each with the same pinout in the
same miniature SOT23 package. The MAX4501 and
MAX4502 specify higher on-resistance but shorter on/off
times. The MAX4514 and MAX4515 have lower onresistance but longer switching times. Another negative
consequence of low on-resistance can be the higher
IN
OFF
ON
OFF
Q = (∆V OUT )(C L )
Figure 5. Charge injection from the switch-control signal causes a
voltage error at the analog output.
8
When the T-switch is on, S1 and S2 are closed and S3 is
open. In the off state, S1 and S2 are open and S3 is closed.
In the off state, the signal tries to couple through the offcapacitance of the series MOSFETs, but is shunted to
ground by S3. Comparing off-isolation at 10MHz for a
video T-switch (MAX4545) vs. a standard analog switch
(MAX312), the result is dramatic: -80dB vs. -36dB for the
standard switch.
remains stored on C when S1 opens. The high-impedance
buffer then maintains VH constant over the ADC’s conversion time. For short acquisition times, the track/hold’s
capacitor must be small, and S1’s on-resistance must be
low. On the other hand, charge injection can cause VH to
change by ±∆VOUT (a few millivolts), thereby affecting the
accuracy of the following ADC.
Having reviewed these fundamentals, we now focus on
new and innovative switches for special applications.
Smaller packages
T-switches for higher frequencies
Other advantages of CMOS analog switches are small
packages and no mechanical parts (unlike reed relays).
Maxim offers a small video switch (MAX4529) as well as
a standard, low-voltage SPDT switch (MAX4544). Both
come in 6-pin SOT23 packages and operate from supply
voltages in the +2.7V to +12V range. The MAX4544 is
the smallest SPDT analog switch available.
The T-switch is suitable for video and other frequencies
above 10MHz. It consists of two analog switches in
series, with a third switch connected between ground and
their joining node. This arrangement provides higher offisolation than does a single switch. The capacitive
crosstalk for an off T-switch typically rises with frequency due to the parasitic capacitances in parallel with
each of the series switches (Figure 7). The problem in
operating a high-frequency switch is not turning it on, but
turning it off.
As mentioned earlier, Maxim offers many variations of
popular analog switches like the CD4066. For example, a
new family of low-cost quad analog switches has been
released (MAX4610/MAX4611/MAX4612). The
MAX4610 is a pin-compatible upgrade to the industrystandard CD4066, but with lower supply voltage (as low
as +2V) and higher accuracy: channel matching to within
4Ω max, and channel flatness to within 18Ω max. These
parts offer three different switch configurations, and their
lower on-resistance (<100Ω at 5V) suits low-voltage
applications. A tiny 14-pin TSSOP package (6.5 x 5.1 x
1.1mm3 max) saves board space.
S1
VS
VH
C
ESD-protected switches
Based on the success of Maxim’s ESD-protected interface
products, ±15kV ESD protection was added to some of its
new analog switches. Maxim now offers the first switches
with ±15kV ESD protection per IEC 1000-4-2 Level 4
(the highest level). All analog inputs are ESD tested using
the Human Body Model, as well as the Contact and AirGap Discharge Methods specified in IEC 1000-4-2. The
MAX4551/MAX4552/MAX4553 switches are pin
compatible with many standard quad-switch families such
as the DG201/DG211 and MAX391. To round out
standard multiplexer families like the 74HC4051 and
MAX4581, Maxim has also released ESD-protected
multiplexers: the MAX4558/MAX4559/MAX4560. From
now on, you need not use costly TransZorbs™ to protect
your analog inputs.
Figure 6. A typical track/hold function requires precise control of
the analog switches.
IN
CS
CS
S1
S3
OUT
S2
VIDEO
T-SWITCH
S1
S2
S3
ON
ON
OFF
ON
OFF
OFF
ON
OFF
Figure 7. The T-switch configuration attenuates RF frequencies that
couple through the stray capacitance between the source
and drain of an open (off) switch.
TransZorb is a trademark of General Semiconductor Industries, Inc.
9
Fault-protected switches
Force-sense switches
The supply-voltage rails for an analog switch restrict the
allowed range for input signal voltage. Although
normally this restriction is not a problem, in some cases
the supply voltage can be turned off with analog signals
still present. That condition can permanently damage the
switch, as can transients outside the normal range of the
power supply. Maxim’s new fault-protected switches and
multiplexers guarantee an overvoltage protection of ±25V
and a power-down protection of ±40V, along with Railto-Rail® signal handling and the low on-resistance of a
normal switch. Also, the input pin assumes a high
impedance during fault conditions, regardless of the
switch state or load resistance. Only nanoamperes of
leakage current can flow from the source (Figure 8).
Recently, Maxim released a new family of analog switches
in which different switch types reside in the same package.
The MAX4554/MAX4555/MAX4556 devices, for
instance, are configured as force-sense switches for Kelvin
sensing in automated test equipment. Each part contains
low-resistance, high-current switches for forcing current,
and higher-resistance switches for sensing voltage or
switching guard signals. On-resistance is only 6Ω for the
current switches, and only 60Ω for the sensing switches at
±15V supply voltages. The MAX4556 contains three
SPDT switches with break-before-make action.
Typical force-sense applications are found in high-accuracy
systems and in measurement systems that involve long
distances (Figure 9). For 4-wire measurements, 2 wires
force a voltage or current to the load, and 2 other wires
connected directly to the load sense and the load voltage.
If the switch is on, the COM output is clamped to the
supply by two internal “booster” FETs (N2, P2 in Figure 8).
Thus, the COM output remains within the supply rails
and delivers a maximum of ±13mA depending on the
load, but without a significant current at the NO/NC pin.
The fault-protected switches MAX4511/MAX4512/
MAX4513 are pin compatible with the DG411/DG412/
DG413 and DG201/DG202/DG213 types. Note that
signals pass equally well in either direction through an
ESD- and fault-protected switch, but these protections
apply only to the input side.
A 2-wire system senses load voltage at the ends of the force
wires opposite the load. Load voltage is lower than the
source voltage because the forcing voltage or current causes
a voltage drop along the wires. The longer the distance
between source and load, the larger the load current; the
higher the conductor resistance, the larger the degradation.
The resulting signal reduction can be overcome by using a
4-wire technique, in which the two additional voltagesensing conductors carry negligible current.
NORMALLY OPEN SWITCH CONSTRUCTION
V+
P2
HIGH
FAULT
P1
COM_
NO_
(NC_)
N1
LOW
FAULT
ON
IN_
GND
N2
V-ESD DIODE
NC SWITCH
Figure 8. This internal structure shows the special circuitry in a fault-protected analog switch.
Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
10
voltage ratios from an input reference voltage, internal
precision resistor-dividers, and a multiplexer for selecting
between different inputs.
V
Two of these devices (the MAX4539/MAX4540) can
balance two major errors associated with an ADC system:
offset and gain error. Using the internal precision voltage
dividers, these devices measure gain and offset in just a
few steps, controlled through the serial interface of a
microcontroller. The reference ratios 15/4096 and
4081/4096 (with respect to the external reference voltage)
are accurate to 15 bits. The ratios (5/8)(V+ - V-) and
V+/2 are accurate to 8 bits.
FORCE VOLTAGE
SENSE VOLTAGE
FEEDBACK
MEASURED
RESISTANCE
V
SENSE VOLTAGE
VOLTAGE
MEASUREMENT
FORCE VOLTAGE
VOLTAGE SOURCE
WIRE AND TERMINAL RESISTANCE
The cal-mux first applies half the supply voltage to verify
that power is present. The system then measures zero
offset and gain error and forms an equation to correct the
subsequent readings. Zero input voltage, for example,
should produce a digital zero output. The cal-mux calibrates for offset error by applying a very small input
voltage of 15/4096 referred to (VREFHI - VREFLO). For a
12-bit ADC with 4.096V reference, 15/4096 equals 15mV
and also 15LSB. The digital output, therefore, should be
binary 000000001111. To measure offset error, the
microcontroller simply records the difference between
binary 000000001111 and the ADC’s actual output.
ARROWS INDICATE SIGNAL DIRECTION, NOT POLARITY
Figure 9. In this four-wire resistance measurement (constant voltage)
technique, two wires force and two other wires sense the
measured voltage.
The new force-sense switches simplify many applications, such as switching between one source and two
loads in a 4-wire system. They are suitable for use in
high-accuracy measurement systems such as nanovoltmeters and femto-ammeters, and for 8- or 12-wire forceand-sense measurements using the guard wires of triax
cables. For more information, please see the MAX4554/
MAX4555/MAX4556 data sheet.
To measure gain error, the cal-mux applies a voltage of
4081/4096 referred to (VREFHI - VREFLO). The microcontroller then records the difference between binary
111111110000 and the ADC’s digital output. Knowing
the ADC’s offset and gain error, the system software
constructs calibration factors that adjust the subsequent
outputs to produce correct readings. The cal-mux then
serves as a conventional multiplexer, but with the capability to periodically recalibrate the system.
Calibration multiplexers
Calibration multiplexers (cal-muxes) are used in precision
ADCs and other self-monitoring systems. Their combination of different components in one package has not been
offered before: analog switches for generating accurate
11
How to simplify
the interface
between
microcontroller
and temperature
sensor
effective resolution drops to 7 bits. To achieve 8-bit
resolution, either add gain via an external op amp or
lower the ADC’s reference voltage (which may reduce
the accuracy of some ADCs).
• The error budget is tight. Combining the error from
the thermistor-resistor combination or analog-sensor
device with those contributed by the ADC, the
amplifier offset voltage, the tolerance of gain-setting
resistors, and the voltage reference error may be more
error than your system can tolerate.
• You want a linear temperature-to-code transfer
function and you’re using a thermistor. The transfer
function for thermistors is very nonlinear, but it may be
sufficiently linear over the narrow temperature range
required in many applications. You can compensate for
the nonlinearity with a look-up table, but this approach
requires resources that may not be available.
Temperature is an analog quantity, but digital systems often
use temperature to implement measurement, control, and
protection functions. If you apply the right techniques and
components, the necessary conversion of analog temperature to digital information won’t be difficult.
• ADC inputs are limited. If the number of temperatures
you want to measure exceeds the number of ADC inputs
available, you may need to add a multiplexer, which will
increase the cost and development time.
Reading temperature with a microcontroller (µ C) is
simple in concept. The µC reads the output code of an
analog-to-digital converter (ADC) driven by a thermistorresistor voltage divider, analog-output temperature
sensor, or other analog temperature sensor (Figure 1). The
ADC built into some controllers can simplify this design.
ADCs require a reference voltage, which can be generated
by an external device. For example, the reference voltage
for a thermistor sensor is usually the same as that applied to
the top of the resistor-thermistor voltage divider. However,
the following complications can arise in these systems:
• The number of µC I/O pins is limited. This won’t be an
issue for an internal ADC, but an external serial ADC
will require two to four I/O pins as an interface to the µC.
The design problems are simplified if you use a temperature sensor with a digital interface. Similarly, temperature
sensors with time- or frequency-based outputs can
alleviate the measurement problem when ADC inputs and
µ C I/O pins are in short supply (Figure 2). The
MAX6576 temperature sensor, for example, produces an
output square wave whose period is proportional to
absolute temperature. It comes in a 6-pin SOT23 package
that requires very little board space. A single I/O pin
interfaces this device to a µC; after its internal counter
measures the period, the µC calculates the temperature.
• The sensor’s output-voltage range is significantly
smaller than the ADC’s input-voltage range. A typical
ADC for this purpose might have 8-bit resolution and a
2.5V reference voltage, which is normally equivalent to
the input-voltage range. If the sensor’s maximum output
for the temperature range of interest is only 1.25V, the
+2.7V TO +5.5V
V+
VDD
R1
VREF
MAX6576
MAX6577
µC
ANALOG INPUT
ADC
TS0
THERMISTOR
TS1
Figure 1. In this simple interface, the ADC’s reference voltage is
derived from the power-supply voltage. An analog temperature sensor can replace the thermistor-resistor voltage
divider. In that case, the ADC (which can be internal to the
µC) requires a reasonably accurate voltage reference.
µC
OUT
I/O
GND
Figure 2. The MAX6576 produces a square wave with period proportional to absolute temperature; the MAX6577 produces an
output frequency proportional to temperature. The resulting
proportionality constant is set to one of four values by the
TS0 and TS1 pins. No external components are necessary.
12
Applying either ground or the positive supply voltage to
each of two logic inputs selects one of four period/
temperature proportionality constants between 10µs/°K
and 640µs/°K.
The first sensor holds the line low for a period proportional
to temperature (5µs/°K) and then releases it. After a second
time delay, selected by setting the programming pins for a
larger proportionality constant, the second MAX6575 pulls
the I/O low and holds it for an interval defined by 5µs/°K.
Four MAX6575s can be connected to the I/O line this way.
Four more MAX6575s of the other, longer-delay version
can be added to the same I/O line. The MAX6575L has
delay multipliers ranging from 5µs/°K to 80µs/°K, and the
MAX6575H delay multipliers range from 160µs/°K to
640µ s/°K. Thus, as many as eight MAX6575s can be
located in different places around the system, connected to
the µC by a single I/O line.
A related temperature sensor (MAX6577) generates an
output square wave whose frequency/temperature factor
is programmable between 0.0675Hz/°K and 4Hz/°K.
Both devices simplify temperature acquisition by
reducing the required PC board real estate, component
count, and analog/digital I/O resources. They transmit
temperature data to the µC through a single digital I/O
pin, and the addition of a single optical isolator makes
them ideal for applications that require electrical isolation
between the sensor and the CPU.
For some systems, the information needed is not the exact
temperature, but whether the temperature is above or
below a specific value. This information can trigger a
cooling fan, air conditioner, heater, or other environmental-control element. In system-protection applications, an “overtemperature bit” can trigger an orderly
system shutdown to avoid losing data when the system
power is cut off. This single bit of information can be
obtained by measuring temperature as in the examples
above, but that approach requires more software and
hardware than the function demands.
For measuring multiple temperatures at various locations,
the choices become more complicated. Thermistors or
conventional analog sensors can be placed in appropriate
locations and connected to the ADC inputs, provided the
ADC has sufficient inputs available. As an alternative, the
MAX6575 transmits temperature data directly to the µC;
as many as eight MAX6575s can be connected to a single
µC I/O input. A single I/O trace connects the µC to these
eight MAX6575s (Figure 3). To measure temperature,
the µC briefly pulls the I/O line low, and after a short
delay the first MAX6575 also pulls the I/O line low. This
time delay is proportional to absolute temperature, with a
proportionality constant programmed using two pins on
the MAX6575.
µC START
PULSE
tD1
VCC
NO. 1
NO. 2
tL1
tL2
tD2
Replacing the ADC in Figure 1 with a voltage comparator
produces a simple 1-bit output that can drive a single I/O
pin on the µC (Figure 4). Again, the thermistor shown can
be replaced by an analog voltage-output temperature
NO. 8
TIME DELAY tLN
∝ TEMP
tL8
tD8
10k
µC
+2.7V TO +5.5V
+2.7V TO +5.5V
MAX6575L
NO. 1
+2.7V TO +5.5V
MAX6575L
NO. 2
TS0
TS0
TS1
TS0
TS1
TS1
GND
GND
MAX6575H
NO. 8
GND
Figure 3. Using a delay scheme to encode temperature information, multiple MAX6575s transmit up to eight temperatures to the µC through a single
digital I/O pin.
13
As with the MAX6575, connecting several MAX6501s or
MAX6503s to a single I/O trace enables the µC to be
notified when temperature crosses the threshold at one or
more locations. If the system must know which location
has crossed the threshold, each switch output must be
connected to a separate I/O pin.
V+
R2
R1
I/O
µC
These sensors measure their own die temperatures, and
because die temperature closely tracks lead temperature,
each sensor should be placed so its leads assume the
temperature of the component being monitored. In some
cases, however, you must measure a temperature not tightly
coupled to the sensor—such as that of a power ASIC,
whose die can be much hotter than the surrounding board.
An internal temperature sensor may enable the ASIC to
shut itself down in response to a temperature fault, but
that capability alone lacks accuracy, and it seldom warns
the system of an impending thermal overload.
R3
THERMISTOR
Figure 4. Combining a sensor with a comparator yields a 1-bit digital
output that can warn the µC of temperature excursions
beyond a predetermined threshold or trip point.
sensor. Most such devices have a relationship between
temperature and output voltage that is unaffected by
supply voltage. To preserve immunity from supplyvoltage variations, connect the top of the comparator’s
resistor-divider to a voltage reference instead of the
supply voltage.
By adding an externally accessible P-N junction to the
ASIC die, you can measure die temperature directly by
forcing two or more different forward currents through
the sensing junction and measuring the resulting voltages.
The difference between the two voltages is proportional
to the absolute die temperature:
The system can be simplified by replacing the sensorcomparator combination with a thermal switch like the
MAX6501. This monolithic device combines the functions of a sensor, comparator, voltage reference, and
external resistors. When temperature exceeds the preset
trip level, the open-drain output goes low. Some devices
in this family have open-drain outputs that go low when
temperature falls below the trip point (MAX6503), and
others have push/pull outputs that go high when temperature goes either above or below the trip point (MAX6502,
Figure 5, or MAX6504). In addition, the hysteresis can
be set to 2°C or 10°C by connecting a package pin to V+
or ground. The available trip temperatures range from
-45°C to +115°C in 10°C increments.
V2 − V1 =
where I1 and I2 are the two current levels forced through
the P-N junction, V1 and V2 are the resulting forward
voltages across the junction, k is Boltzmann’s constant, T
is the absolute temperature of the junction in degrees
Kelvin, and q is the electron charge.
This measurement, of course, requires precision circuitry
for generating the accurate current ratios and measuring
very small voltage differences while rejecting the noise
produced by large transients on the power ASIC die.
Fortunately, Maxim’s remote-junction temperature
sensors integrate these precision analog functions with a
simple and versatile digital interface.
+2.7V TO +5.5V
VCC
VCC
MAX6502
µC
GND GND HYST
GND
kT  I2 
1n
q  I1 
The MAX1618, for example, measures remote-junction
temperatures with 8-bit (1°C) resolution and communicates
the result to a µC over the SMBus (Figure 6). Originally
designed for monitoring the CPU temperature in PCs, this
device has other features that remove some of the
controller’s overhead. For example, the MAX1618
monitors a remote-junction temperature with a window
comparator and interrupts the µC when temperature goes
Figure 5. The MAX6502 produces a logic-high output when its temperature exceeds the preset threshold value.
14
above or below the limit thresholds previously downloaded to its registers by the µC. Rather than poll the
MAX1618 continually, the µC can set the temperature
thresholds on start-up and then ignore the MAX1618 until
a thermal problem requires its attention.
+3.0V TO +5.5V
10k
VCC
SMBCLK
CPU, ASIC,
or Discrete
Transistor
MAX1618
DXP
ON-CHIP
P-N
JUNCTION
10k
SMBDATA
2200pF
DXN
10k
GND
Available in a 10-pin µMAX package, the MAX1618 can
be placed close to the junction being measured. In turn,
the resulting short trace lengths between the sense
junction and MAX1618 help to avoid noise pickup.
SMBus
SERIAL
INTERFACE
(TO µC)
ALERT
Figure 6. The MAX1618 measures the temperature of an external P-N
junction (part of a discrete transistor, ASIC, or CPU) by
forcing currents through the junction and measuring the
resulting forward voltages.
15
NEW PRODUCTS
The MAX106 is an 8-bit, monolithic,
bipolar analog-to-digital converter (ADC)
with a 600Msps digitizing rate. Pin compatibility with the 1Gsps MAX104 allows easy
upgrades. The MAX106 is ideal for highspeed communications, instrumentation,
and data-acquisition applications that
require wide bandwidth, good linearity, and
a high level of dynamic performance at
lower sampling rates.
Unlike other high-speed 8-bit ADCs,
the MAX106 achieves a 47.8dB SINAD
and 57.5dB SFDR at the 300MHz Nyquist
frequency. It maintains this performance
(within 0.1dB) for input frequencies to
600MHz, i.e., twice the Nyquist frequency.
The MAX106 achieves high performance through innovative design and the
use of Maxim’s proprietary 27GHz GST-2
bipolar process. A track/hold (T/H) with
fully differential input employs Schottky
diodes and laser-trimmed resistors to
achieve 2.2GHz full-power bandwidth,
aperture jitter less than 1ps, and typical
integral nonlinearity (INL) and differential
nonlinearity (DNL) values less than
SOT temperature
sensors have
single-wire
outputs
The MAX6576/MAX6577 temperature
sensors have a single-wire digital interface
that communicates temperature to a microprocessor over a single control line. The
MAX6576 converts ambient temperature to
a square wave with periods proportional to
absolute temperature (°K). The MAX6577
converts ambient temperature to a square
wave with frequency proportional to
absolute temperature. Hard-wiring the two
±0.25LSB. As a further advantage, the
proprietary decoding scheme ensures a low
occurrence of metastable states (1 in 1015
clock cycles), with no error exceeding
1LSB.
Proper packaging is also critical to
achieving good performance at these
frequencies. The MAX106 comes in
a 25mm x 25mm x 1.4mm, 192-contact
Enhanced Super Ball-Grid Array
(ESBGA™) package that minimizes
parasitic effects, provides controlledimpedance signal paths, and eliminates the
need for heatsinking in most applications.
A demultiplexer with 8 or 16 outputs
(selectable) facilitates the digital interface
by slowing the 600Msps data to only
300Mwords/second, ported to two
parallel, differential, 8-bit, low-voltage
PECL outputs. The MAX106 also supports single-port operation at 600Msps
sampling rates. It presents data in offsetbinary format and includes an output
clock and overrange bit. The MAX106
operates from ±5V supplies and supports
an output interface in the +3V to +5V
range.
The MAX106 is specified for the commercial temperature range (0°C to +70°C).
An evaluation kit is also available. Contact
factory for availability.
ESBGA is a trademark of Amkor/Anam.
time-select pins to VDD or GND selects this
square-wave period or frequency range
from one of four preset values.
The MAX6576/MAX6577 feature an
accuracy of ±3°C max (±0.8°C typ) at
+25°C, and ±5°C max at +125°C. They
operate from a +2.7V to +5.5V supply and
draw supply currents of only 140µA typ,
making them ideal for use in portable,
battery-powered equipment. Available in
space-saving 6-pin SOT23 packages, they
are specified for operation over the automotive temperature range (-40°C to
+125°C). Prices start at $0.74 (2500-up,
FOB USA).
12- and 14-bit
DACs with 1LSB
INL eliminate
power-up glitch
The MAX5170–MAX5177 serialinput/voltage-output, 12- and 14-bit
digital-to-analog converters (DACs)
feature proprietary circuitry for eliminating
power-up glitches. Unlike DACs with
undesirable output glitches of 2V to 3V at
power-up, these outputs are virtually
“glitch free,” with excursions less than
5mV. These devices also guarantee monotonicity, with ±1LSB INL and ±1LSB max
DNL at 14-bit resolution.
These low-power devices operate from
a single supply voltage of +3V or +5V,
and draw supply currents of only 350µA
max. This current drops to 1µ A in the
power-down mode. A power-up reset
allows the user to select an initial output
state of either zero or midscale. The
amplifier’s user-accessible output and
inverting input allows remote sensing,
specific gain configurations, and highoutput-drive capability for a wide range of
force-sense applications. The buffered
output is capable of driving 5kΩ | | 100pF
or 4–20mA loads.
These eight SPI™-, QSPI™-, and
MICROWIRE™-compatible serial interface devices are available in space-saving
16-pin QSOP packages. The 12-bit
MAX5174/MAX5176 and 14-bit MAX5170/
MAX5172 are voltage-output versions.
The 12-bit MAX5175/MAX5177 and 14-bit
MAX5171/MAX5173 are force-sense
versions. Prices start at $3.15 (1000-up,
FOB USA).
SPI™/QSPI™ are trademarks of Motorola, Inc.
MICROWIRE™ is a trademark of National
Semiconductor Corp.
MAX5170 FAMILY
(Virtually “Glitch Free”)
3
500mV/div
High-performance
8-bit ADC with
track/hold
converts at
600Msps
~5mV
SUPPLY
VOLTAGE
2
1
0
VOUT
POWER-UP TIME
500ms/div
16
NEW PRODUCTS
2.7V rail-to-rail
instrumentation
amplifiers achieve
115dB CMRR
The MAX4194–MAX4197 family of
micropower instrumentation amplifiers
have Rail-to-Rail® capability and a threeop-amp topology that combines precision
specifications with operation from a single
supply voltage in the +2.7V to +7.5V
range. Supply current is just 93µ A in
normal operation and 8µA in shutdown.
Enable time is 500ms, and the unity-gain
settling time to 0.1% is 85µs.
These devices conserve battery life in
low-voltage, battery-powered systems by
pulsing the amplifier on and off with a
low duty cycle. In addition to low power
consumption, the devices have an excel-
Hot-swap
controller speeds
start-up and
improves fault
response
The MAX4370 is a Hot-Swap™ controller for 3V to 12V systems. Upon
insertion into a live backplane, it regulates
the inrush current while monitoring two
types of fault condition: low-amplitude/
long-duration current transients, and fast
high-amplitude current transients. Hot
Swap controllers that don’t regulate this
start-up current introduce long delays that
vary with component tolerances. The
MAX4370 reduces this variation and
eliminates start-up delays without collapsing the backplane supply.
After the start-up period expires, two
comparators in the DualSpeed/BiLevel™
protection circuitry (one fast, one slow)
operate simultaneously to detect the two
power-supply overcurrent faults (fast, highamplitude transients or long-duration, lowamplitude transients). If either fault occurs,
the MAX4370 asserts a latched output alert
and disconnects the main supply by turning
off the external MOSFET. Because this
proprietary scheme (patent pending) more
lent DC common-mode rejection rate
(CMRR) of 95dB to 115dB, depending on
the gain. The unity-gain-stable MAX4194
is configurable for gains up to +1000V/V.
The CMRR is 115dB at the highest gain.
The MAX4195/MAX4196/MAX4197 are
internally configured for gains of unity,
+10V/V, and +100V/V, respectively.
The MAX4195 exhibits 95dB CMRR
and achieves a 220kHz bandwidth. The
MAX4196/MAX4197 achieve bandwidths
of 34kHz and 3.2kHz, and exhibit 115dB
CMRR. All parts feature rail-to-rail
outputs that can drive a 5kΩ load to
within 100mV of each rail. The
MAX4194–MAX4197 amplifiers are
available in 8-pin SO packages. Prices
start at $1.60 (1000-up, FOB USA).
Rail-to-Rail is a registered trademark of Nippon
Motorola, Ltd.
easily differentiates faults that are disruptive and catastrophic from those that are
benign, the controller is less prone to false
triggering than are other Hot Swap devices.
The start-up timeout period and the
slow-comparator response time are
programmed separately with external
capacitors, and the overcurrent thresholds
are programmed with an external currentsense resistor. The MAX4370 is available
in an 8-pin SO package, with prices
starting at $1.95 (1000-up, factory direct,
FOB USA).
Hot Swap is a trademark of Linear Technology
Corp.
DualSpeed/BiLevel is a trademark of Maxim
Integrated Products.
DUAL-SPEED/BILEVEL FAULT DETECTION
PROTECTS AGAINST CATASTROPHIC
CURRENT SURGES
Rail-to-rail SOT23
op amps include
gain-setting
resistors
Rail-to-Rail op amps in the low-cost
GainAmp™ family (MAX4174/MAX4175
and MAX4274/MAX4275) include precision gain-setting resistors and VCC/2 bias
networks. The factory-trimmed internal
resistors provide fixed inverting gains from
-0.25V/V to -100V/V and fixed noninverting gains from +1.25V/V to +101V/V.
They also yield 0.1% gain accuracy while
minimizing layout size and cost.
GainAmps draw only 300µA, operating
from a single supply in the +2.5V to +5.5V
range. Optimal compensation of each device
yields exceptional gain-bandwidth products
(as high as 23MHz for AV between +25V/V
and +101V/V). High-voltage fault protection
at each input allows the devices to withstand up to ±17V without drawing excessive current.
The GainAmp family includes three
versions: single/dual/quad open-loop and
unity-gain stable (MAX4281/MAX4282/
MAX4284), single/dual fixed-gain
(MAX4174/MAX4274), and single/dual
fixed-gain with internal VCC/2 bias at the
noninverting input (MAX4175/MAX4275).
(Internal V CC /2 bias simplifies singlesupply circuitry.)
The input common-mode voltage
range for the open-loop amplifiers extends
from 150mV below the negative supply to
within 1.2V of the positive supply. Each
output swings rail-to-rail and maintains
excellent DC accuracy while driving a
1kΩ load. The amplifiers maintain stability
for capacitive loads up to 470pF, without
need for an external isolation resistor.
GainAmps come in 5-pin SOT23 packages
with prices starting at $0.60 (1000-up,
FOB USA).
GainAmp is a registered trademark of Maxim
Integrated Products.
MAX4370
17
NEW PRODUCTS
Precision, lowdropout voltage
references offer
15ppm/°C stability
A family of low-dropout micropower
voltage references (MAX6012/MAX6021/
MAX6025/MAX6030/MAX6041/
MAX6045/MAX6050) offers a low temperature coefficient of 15ppm/°C over the
commercial temperature range (0°C to
+70°C). Available in tiny 3-pin SOT23
packages, their respective voltage outputs
are 1.250V, 2.048V, 2.500V, 3.000V,
4.096V, 4.500V, and 5.000V. A proprietary curvature-correction circuit and
laser-trimmed thin-film resistors provide
the low tempco and tight initial accuracy.
Unlike conventional shunt-mode
(2-terminal) references whose external
resistor wastes supply current, Maxim’s
series-mode devices require no external
resistor. Drawing a quiescent supply
current of 27µA, they can sink or source
load currents as high as 500µA.
MAX SUPPLY CURRENT (µA)
Because these internally compensated
references require no external compensation capacitor, either, they save valuable
board area in space-critical applications.
Line regulation is <8µV/V, load regulation is <15µ V/µ A, and the operation
remains stable for load capacitance up to
2.2nF. Low dropout voltage (200mV) and
very low supply current make these references ideal for low-voltage, batteryoperated systems. Prices start at $1.35
(1000-up, FOB USA).
65
AD158x
MAX60xx
35
20
The MAX4311/MAX4312/MAX4314/
MAX4315 are single-supply, 4- and 8channel multiplexer-amplifiers (muxamps). Their video output buffers have
bandwidths as high as 345MHz
(MAX4311). Unlike mux-amps that
require ±5V bipolar supplies, these
guarantee operation from a single supply
voltage in the +4.0V to +10.5V range.
They also operate between ±2.0V to
±5.25V in dual-supply applications.
Rail-to-rail outputs, ground-sensing
inputs, and low (6.1mA) quiescent supply
currents suit these mux-amps for video
switching in portable, battery-powered
applications. In addition, their low cost,
ultra-low switching glitch (10mVp-p), and
excellent video specifications make them
suitable for consumer applications
including video teleconferencing equipment, set-top boxes, and video surveillance
systems.
50
MAXIMUM DRIFT (ppm/°C)
78MHz, slew rates to 430V/µs, low differential gain/phase (0.06%/0.08°), and a
spurious-free dynamic range (SFDR) of
-95dBc (MAX4314/MAX4315). Their
optional disable mode reduces supply
currents to 560µA and places the outputs
in a high-impedance state, making these
devices useful in multiplexing applications
that require larger switch matrices.
The MAX4311/MAX4314 are offered
in 14-pin SO and 16-pin QSOP packages,
and the MAX4312/MAX4315 are offered
in 16-pin SO and QSOP packages. Prices
start from $0.44 per channel (100,000-up,
factory direct, FOB USA).
ULTRA-LOW SWITCHING GLITCH
5V
IN1
(2.5V/div)
0V
OUT
(10mV/div)
MAX4311
The MAX4311/MAX4312/MAX4314/
MAX4315 offer 0.1dB gain flatness to
Rail-to-rail, quad
SPDT analog
switch has ±40V
fault protection
The MAX4533† is the new member
of Maxim’s family of fault-protected
switches. A quad, single-pole/doublethrow (SPDT) device, it is pin compatible
with the nonprotected industry-standard
MAX333 and MAX333A.
LT1460
135
4/8-channel video
mux-amps operate
from single +5V
supply
The fault-protected MAX4533
provides ±40V of input protection with
power off, and as much as ±25V of overvoltage protection during power-up and
power-down. The input terminals become
open-circuited during a fault condition,
allowing only nanoamperes of leakage
into the source. To ensure unambiguous
18
TIME (20ns/div)
outputs, the switch output clamps to the
appropriate supply voltage during a fault
condition and delivers as much as 13mA
of proper-polarity load current.
The MAX4533 also features rail-to-rail
signal handling capability, low on-resistance of 175Ω max, and channel-to-channel
on-resistance matching to 6Ω max. The
fault-protected input leakage is 0.5nA at
+25°C and 10nA at +85°C. The switch
operates from a single supply voltage of
+9V to +36V, or from dual supplies in the
±4.5V to ±18V range. The digital-input
thresholds (+0.8V and +2.4V) ensure
compatibility with TTL/CMOS logic. The
MAX4533 is available in 20-pin plastic
DIP, SO, and SSOP packages, with prices
starting at $2.32 (1000-up, FOB USA).
† Patent pending.
NEW PRODUCTS
Triple audio/visual
crosspoint
switches have
serial control
The MAX4548/MAX4549 programmable crosspoint switches are well suited
for multimedia (audio/video) applications.
Each switch includes three 3-input/
2-output (triple 3x2) crosspoint matrices,
and each matrix has a shunt input to
improve off-isolation. Each output is
programmable for regular mode or for a
selectable soft-switching mode that
provides “clickless” audio operation.
Typical on-resistances (22Ω with a +5V
supply) are flat to within 2Ω and matched
(between channels) to within 5Ω.
The MAX4548/MAX4549 operate on
a single supply voltage in the +2.7V to
+5.5V range. Each includes a set of
resistive voltage dividers that are independently selectable via the serial interface,
which provides a DC bias for each output
when the inputs are AC-coupled. Other
specifications include 0.07% THD (with
600Ω load), off-isolation of -85dB at
20kHz (-72dB at 10MHz), and crosstalk
of -85dB at 20kHz (-55dB at 10MHz).
The MAX4548 2-wire serial interface
is compatible with the I 2 C™ standard,
and the MAX4549 3-wire serial interface
is compatible with the SPI/QSPI/
MICROWIRE standards. Both devices are
available in 36-pin SSOP packages
specified for the extended-industrial
temperature range (-40°C to +85°C).
Prices start at $3.12 (1000-up, FOB USA).
I2C™ is a trademark of Philips Corp.
Single chip drives
pager-vibrator
motor
The MAX1749 is a buzzer/vibrator
motor driver for pagers and wireless
handsets. Unlike conventional approaches in
which the motor strength decays with
battery voltage, this device enables the mo-
Low-voltage analog
mux/switches
have ±15kV ESD
protection
Lowpass switchedcapacitor filters
have 8th-order
elliptic response
The MAX4558/MAX4559/MAX4560
are low-voltage CMOS analog devices
configured as an 8-to-1 multiplexer
(MAX4558), dual 4-to-1 multiplexer
(MAX4559), and triple SPDT switch
(MAX4560). These parts withstand electrostatic discharge (ESD) without latchup
or damage, to ±15kV (Human Body
Model), ±12kV (IEC 1000-4-2 Air-GapDischarge Method), and ±8kV (IEC 10004-2 Contact-Discharge Method).
The MAX7400/MAX7403/MAX7404/
MAX7407 are 8th-order elliptic, lowpass
switched-capacitor filters. Whether
operating from +5V (MAX7400/MAX7403)
or +3V (MAX7404/MAX7407), they provide corner frequencies from 1Hz to
10kHz and draw supply currents of only
2mA, making them ideal for low-power
anti-aliasing and post-DAC filtering applications. Shutdown mode lowers the supply
current to just 0.2µA.
Pin compatible with the industrystandard 74HC4051/74HCH052/74HC4053
switches, these devices operate from a
single supply in the +2V to +12V range or
from dual supplies in the ±2V to ±6V
range. On-resistances are guaranteed to
≤220Ω with a +5V supply, to ≤160Ω with
±5V supplies, and are matched within 2Ω
(typ) for a single device.
The MAX7400/MAX7404 provide a
sharp rolloff with a 1.5 transition ratio and
80dB of stopband rejection, and the
MAX7403/MAX7407 provide a sharper
rolloff (1.2 transition ratio) with 58dB of
stopband rejection. The low output offset
(±4mV) can be further minimized via an
offset-adjustment pin (OS) in all four filters.
Each switch handles rail-to-rail input
signals. The off-leakage current is only
1nA at +25°C, and only 10nA at +85°C.
To ensure TTL/CMOS compatibility with
single 5V or dual ±5V supplies, all digital
inputs guarantee 0.8V/2.4V thresholds.
Other specifications include low
(<0.02%) distortion with 600Ω loads, low
(-93dB) crosstalk with 50Ω loads, and
high (-96dB) off-isolation with 50Ω loads.
The MAX4558/MAX4559/MAX4560
come in 16-pin QSOP, DIP, and narrowSO packages, with prices starting at $1.59
(1000-up, FOB USA).
tor to deliver constant force by producing
a constant output voltage throughout its
input range (+2.5V to +6.5V).
Acting as a regulator and logiccontrolled switch, the MAX1749 draws
just 1nA in its off state. Its fixed output is
designed to drive inexpensive single-cell
annunciators. The output is also adjustable, which lets you customize the buzzer
19
The filters’ internal switching can be
self-clocked with an external capacitor or
clocked externally for tighter control of the
corner frequency. Their fixed output
response reduces the design task to simply
selecting a corner frequency by setting the
clock frequency. The parts are available in
8-pin plastic DIP and SO packages, with
prices starting at $1.98 (1000-up, FOB USA).
V+
INPUT
CLK
SHDN
MAX74xx
OUT
COM
OS
strength for load currents up to 120mA.
Other features include output-current
limiting, thermal-overload protection, and
reverse-battery protection.
The MAX1749EUK is available in an
ultra-small 5-pin SOT23 package specified
for the extended-industrial temperature
range (-40°C to +85°C). Prices start from
$0.74 (1000-up, FOB USA).
NEW PRODUCTS
For pulsed load currents such as that
drawn during the transmit burst of a GSM
phone (which operates with a 1:8 duty
cycle), the MAX1687/MAX1688 have a
proprietary control scheme (patent pending)
that lowers the battery drain by recharging a
reservoir capacitor during the off-time.
During the transmit pulse, the DC-DC
converters turn off to eliminate switching
noise at the PA and isolate the battery from
load transients.
A typical 5V PA draws as much as 2A
while transmitting, and a conventional DCDC converter pulls nearly 3A from the
battery: 2A times (5V/3.6V), plus efficiency
losses. The MAX1687/MAX1688 reduce
this current to zero during the transmit
burst, and to less than 0.5A (a 6-times
improvement) when recharging the
reservoir capacitor during the off-time. The
MAX1687 lets you set maximum battery
current; the MAX1688 samples the output
voltage droop, automatically adjusting the
peak inductor current to minimize battery
drain while charging the output capacitor
within the GSM timing cycle.
The MAX1687/MAX1688 require no
external FET, and their internal synchronous rectifier eliminates a Schottky diode
while boosting efficiency to more than
90%. They are available in standard
8-pin SO packages and in small 16-pin
TSSOP packages less than 1.1mm high.
Prices start from $2.20 (1000-up, FOB
USA). A preassembled evaluation kit with
recommended external components
(MAX1688EVKIT) is available to reduce
design time.
The MAX1623 buck regulator provides CPU and bus-termination power in
notebook and desktop computers. The
output voltage is either pin selectable as
3.3V or 2.5V, or adjustable down to 1.1V.
Output accuracy including line and load
regulation is ±1%.
PWM operation allows switching
frequencies as high as 350kHz. Other
MAX1623 features include thermal
protection (T j = +150°C) and a logiccontrolled shutdown mode that lowers the
supply current below 1µA (10µA max).
An internal PMOS power switch and
an NMOS synchronous-rectifier switch,
both rated at 3A/0.1Ω, minimize the
external component count and enable the
device to deliver (for example) 2A at 3.3V
from a +5V supply, with 93% efficiency.
The input-voltage range is +4.5V to
+5.5V, and the typical operating supply
current is 450µA.
The MAX1623 is available in a spacesaving 20-pin SSOP package specified for
the extended-industrial temperature range
(-40°C to +85°C). Prices start from $4.78
(1000-up, FOB USA).
24V and 28V systems, and buck-boost
(SEPIC) converters for automotivepowered systems.
28V PWM step-up
DC-DC converter
delivers high
voltage and
current
A fixed-frequency PWM control
scheme with Maxim’s Idle Mode™
operation minimizes noise and ripple at
light loads while maximizing efficiency
over a wide range of load current. Low
levels of no-load operating current
(500µA) allows efficiencies to 93%, and
the supply current in shutdown drops to
only 3µA. Fast switching (250kHz) allows
use of small surface-mount inductors and
capacitors. Adaptive-slope compensation
and a single compensation capacitor lets
the MAX618 accommodate wide ranges
of input and output voltage.
The MAX618 is a CMOS, PWM,
step-up DC-DC converter that generates
output voltages to 28V and accepts inputs
from 3V to 28V. An internal 2.2A/0.3Ω
switch eliminates the need for external
power MOSFETs and delivers 50% more
output current than comparable 1.5A
devices. Typical applications include
LCD displays, telecom devices, industrial
The MAX618EEE is available in a
thermally enhanced 16-pin QSOP
package (same size as a standard 8-pin
SO) that dissipates up to 1W. The parts
are specified for the extended-industrial
temperature range (-40°C to +85°C),
with prices starting at $3.25 (1000-up,
FOB USA). A preassembled evaluation
kit with recommended external components (MAX618EVKIT) is available to
reduce design time.
STEP-UP DC-DC DELIVERS
50% MORE OUTPUT CURRENT
AND WIDER OPERATING RANGE
1.5
MAX618
OUTPUT CURRENT (A)
The MAX1687/MAX1688 step-up DCDC converters minimize peak battery
current and prevent battery glitches during
the transmit cycle of GSM phones and
wireless LANs. To drive the RF power
amplifier (PA) in a typical cell phone, these
DC-DC converters boost the output of three
NiCd cells or a single 3.6V lithium-ion
(Li+) cell to 5V.
Load current causes the MAX1623 to
shift smoothly between operating modes.
Above 1A it assumes current-mode pulsewidth modulation (PWM) control, in
which constant off-times for the power
switch are followed by on-times proportional to the load current required. Below
1A, it accommodates lower load currents
by turning off both switches to skip entire
cycles.
Synchronous,
switch-mode buck
regulator has 3A
internal switches
Boost converters
drive 2A Tx burst
with 6x-lower
battery current
1.0
VIN = 12V
0.5
VIN = 5V
VIN = 3V
Idle Mode is a trademark of Maxim Integrated
Products.
0
4
6
8
10
12 14 16 18 20
OUTPUT VOLTAGE (V)
20
22
24
26
28
NEW PRODUCTS
Small, highfrequency
step-down
converter has
internal switches
The MAX1644 DC-DC converter is
suited for use in PC cards, CPU daughter
cards, and bus-termination boards. It is the
smallest, highest frequency, and most
efficient device available among 2A DCDC converters with internal switches. To
minimize external components and improve efficiency (to 95%), the MAX1644
includes 0.1Ω typ internal N- and Pchannel MOSFETS for switching and
rectification.
The MAX1644’s current-mode PWM
control scheme features a programmable
constant-off time with switching frequen-
Li+ cell protector is
±0.5% accurate
The MAX1666 is the first Li+ cell
protector to offer ±0.5% accuracy for the
cell-overvoltage threshold. Its accuracy
(vs. that of other protectors) allows the use
of charge voltages much closer to the
cell’s design limits, increasing the amount
of charge stored in a typical 4-cell battery
pack by as much as 2%. The MAX1666 is
also the first to closely monitor cell-to-cell
voltage mismatches and automatically shut
down the pack when a mismatch exceeds
the user-adjusted limit.
cies as high as 350kHz. To maintain high
efficiency during light-load operation, it
also includes a pulse-frequency-modulation (PFM) mode (Idle Mode). The
MAX1644 produces a preset output voltage of 3.3V or 2.5V, or an adjustable
output of 1.1V to 3.8V. The input voltage
range is +3V to +5.5V. Other features
include 1% output accuracy, adjustable
soft-start for limiting inrush current, and
supply currents of 240µ A typ during
operation and 1µA max during shutdown.
The MAX1644 is available in a spacesaving 16-pin SSOP package specified for
the extended-industrial temperature range
(-40°C to +85°C). Prices start from $4.08
(1000-up, FOB USA). A preassembled
evaluation kit (MAX1644EVKIT) with
recommended external components is
available to reduce design time.
alleviates the need for an external voltage
regulator. This LDO regulator accepts
inputs in the +4V to +28V range, and
supplies up to 5mA for other circuitry. A
true “micropower” device, it consumes
only 30µA while operating and <1µA in
shutdown.
The MAX1666 “S” version (16-pin
QSOP) monitors 2-cell packs, the “V”
version (20-pin QSOP) monitors 3-cell
packs, and the “X” version (20-pin QSOP)
monitors 4-cell packs. All parts are
specified for the extended-industrial
temperature range (-40°C to +85°C).
Prices for the MAX1666X start from $2.75
(1000-up, FOB USA).
The MAX1666 provides accurate, useradjustable threshold limits for cell overvoltage (4.0V to 4.4V at ±0.5%), cell
undervoltage (2.0V to 3.0V at ±2.5%), PACK+
Wide Input
cell-to-cell mismatch (0 to 500mV at
Voltage
±10%), and charge/discharge current
Range
(set by the sense resistor at ±10%).
When a fault condition occurs, the
internal power-MOSFET drivers
control external P-channel MOSFETs
to reliably disconnect the cells from
the pack terminals. The MAX1666 can
2 to 4
operate as a stand-alone device or in
Series Cells
conjunction with a pack microcontroller, using its digital interface and
status signals.
The MAX1666’s on-board 3.3V
low-dropout (LDO) linear regulator
PACK-
RSENSE
SRC
VCC
DSO
CGO
DSI
CGI
WRN
PKF
UVO
B4P
B3P
On-Chip
LDO Regulator
Digital
Interface &
Status Signals
MAX1666X
B2P
REF
B1P
GND
OVA
UVA
MMA
PKN
21
Accurate
Adjustable
Threshold
Limits
Single chip
charges Li+ cells
The MAX1667 battery charger complies with Level 2 of the SBS IF Specification v1.0. Offering high efficiency and
support for most battery chemistries, this
one-chip charger for lithium-ion (Li+) cells
contains independent circuitry for voltage
and current regulation, enabling it to make
automatic transitions between constantcurrent and constant-voltage modes during
charging. The MAX1667 charges two to
four series Li+ cells and regulates the
programmed charging voltage to within
±0.8%.
By allowing the duty cycle to exceed
97%, the MAX1667’s advanced synchronous-buck topology ensures a low
input-to-output voltage differential while
maintaining efficiencies greater than 95%.
Its SMBus™-compatible 2-wire interface
accepts programming commands for the
charging voltage and current and reports
status information for the charger and
battery. The charging voltage is 11-bit
programmable from 0 to 18.432V, and the
charging current is 5-bit programmable
from 0 to 1A, 3A, or 4A.
A thermistor in the battery and failsafe protection logic in the MAX1667
inhibits charging if the battery temperature exceeds predetermined limits. The
MAX1667 can signal the host controller
when a battery is installed or removed, or
when power is applied to the charger. A
pin-compatible upgrade for the industrystandard MAX1647 (a Level 2 smartbattery charger), the MAX1667 connects
directly to charge-voltage sources in the
+7.5V to +28V range.
The MAX1667 is specified for the
extended-industrial temperature range
(-40°C to +85°C), and comes in a spacesaving 20-pin SSOP package only 2mm
high. Prices start at $4.95 (1000-up, FOB
USA).
SMBus is a trademark of Intel Corp.
NEW PRODUCTS
Switchedcapacitor voltage
inverters offer
shutdown
The MAX1719/MAX1720/MAX1721
charge-pump inverters are monolithic
CMOS devices in tiny SOT23 packages.
Accepting input voltages in the +1.5V to
+5.5V range, they operate at 12kHz
(MAX1720) or 125kHz (MAX1719/
MAX1721). High efficiency (96%), small
RS-232 receivers
in SOT packages
have ±15kV ESD
protection
The MAX3180E family of single RS232 receivers features ±15kV protection
against electrostatic discharge (ESD). Each
device is designed for space- and costconstrained applications requiring minimal
RS-232 communications. To ensure
compliance with strict European ESD
standards, the receiver inputs are protected
to ±15kV using the IEC 1000-4-2 Air-Gap
Discharge Method, to ±8kV using the IEC
1000-4-2 Contact Discharge Method, and to
±15kV using the Human Body Model.
IC combines UART
and RS-485
transceiver
The MAX3140 combines a complete
UART and RS-485 transceiver in a single
28-pin package. Its SPI/MICROWIREcompatible serial interface saves additional board space and microcontroller I/O
pins, and its pin-programmable network
configurations simplify the installation of
RS-485/RS-422 networks.
The MAX3140 includes a single RS485/RS-422 driver and receiver with true
fail-safe circuitry that guarantees a logichigh receiver output when the receiver
inputs are open or shorted. This feature
provides fault immunity without requiring
complex terminations. The MAX3140
provides software-selectable control of the
half/full-duplex, data-slew-rate, and
phase-control functions. To control slew
external components, and a logic-controlled
1nA shutdown make these devices suitable
for battery-powered and board-level
voltage-conversion applications—such as
generating a -5V analog supply from the 5V
digital supply.
Each part has oscillator-control
circuitry and four power MOSFET
switches. The MAX1720 quiescent current
is a low 50µ A, and all devices deliver
continuous output currents up to 25mA.
Each device guarantees RS-232 performance up to 1.5Mbps, and minimizes
power and heat dissipation by drawing only
0.5µA from a +3V to +5.5V supply. The
MAX3180E/MAX3182E receivers have a
three-state TTL/CMOS receiver output
controlled by an EN logic output. For applications requiring automatic system wakeup, the MAX3181E/MAX3183E receivers
feature an output (INVALID) that indicates
valid RS-232 signals at the receiver input.
The MAX3182E/MAX3183E have
noninverting outputs, and the MAX3180E/
MAX3181E have standard inverting
outputs. All are specified for the extended
temperature range (-40°C to +85°C). They
come in 5-pin SOT23 packages, with prices
starting at $0.66 (1000-up, FOB USA).
rate and minimize EMI, the transceiver
data rate is programmable to 115kbps,
500kbps, or 10Mbps. Independent phase
control in the transmitter and receiver
enables software correction of polarity
reversal in twisted-pair cables.
The UART includes an oscillator
circuit derived from an external crystal,
and a baud-rate generator with softwareprogrammable divider ratios for common
baud rates. It features an 8-word-deep
receive FIFO that minimizes processor
overhead, and provides a flexible interrupt
with four maskable sources, including
address recognition on 9-bit networks.
The MAX3140 operates from a single
+5V supply, and has a 20µ A shutdown
mode (invoked by hardware or software)
in which the receiver remains active. It is
available in a space-saving 28-pin QSOP
package, with prices starting at $4.07
(1000-up, FOB USA).
22
For pin-compatible inverters without
shutdown (allowing a 5-pin instead of a
6-pin package), see the MAX828/MAX829
and MAX870/MAX871. For higher power
applications, the MAX860/MAX861
deliver output currents up to 50mA. For
regulated outputs up to -2V IN , see the
MAX868. T h e M A X 860/MAX861/
MAX868 come in space-saving µ MAX
packages.
The MAX1719/MAX1720/MAX1721
come in 6-pin SOT23 packages, with prices starting at $1.30 (1000-up, FOB USA).
3V RS-485/RS-422
transceivers
feature ±15kV
ESD protection
To meet ±15kV ESD protection
standards, Maxim offers the MAX3483E/
MAX3485E/MAX3486E, MAX3488E/
MAX3490E/MAX3491E 3V RS-485/RS422 transceivers. These devices save space
and cost by eliminating the need for
TransZorbs™ and other external protection
used to meet ESD standards. All transmitter
outputs and receiver inputs are ESDprotected to ±15kV using the Human Body
Model and the IEC 1000-4-2 Air-Gap
Discharge Method, and to ±8kV using the
IEC 1000-4-2 Contact Discharge Method.
Each part contains one driver and one
receiver, and delivers RS-485/RS-422
performance down to V CC = +3V. The
MAX3483E/MAX3488E have slew-ratelimited drivers that minimize EMI and
reduce reflections caused by improperly
terminated cables, allowing error-free data
transmissions to 250kbps. The partially
slew-rate-limited MAX3486E transmits up
to 2.5Mbps, and the MAX3485E/
MAX3490E/MAX3491E can transmit at
12Mbps, making them ideal for high-speed
industrial buses.
For full-duplex operation, use the
MAX3488E/MAX3490E/MAX3491E; the
MAX3483E/MAX3485E/MAX3486E offer
half-duplex operation. The MAX3491E
comes in 14-pin DIP and SO packages; all
others come in 8-pin DIP and SO packages.
Prices start at $1.91 (1000-up, FOB USA).
TransZorb is a trademark of General
Semiconductor Industries, Inc.
NEW PRODUCTS
Integrated
RS-232/UART
saves space,
power, and I/O pins
down, when the receivers remain active to
allow monitoring of external devices, the
ICs draw only 10µ A of supply current.
Each guarantees EIA/TIA-232 outputvoltage levels for data rates as high as
230kbps.
The MAX3110E/MAX3111E are the
world’s first ICs to integrate a UART and
an RS-232 transceiver. Available in single
28-pin SO packages, they combine a fullfeatured universal asynchronous receiver/
transmitter (UART) with an RS-232
transceiver (ESD-protected to ±15kV) and
integrated charge-pump capacitors. The
MAX3110E/MAX3111E SPI/ MICROWIREcompatible serial interface minimizes the
pin count while saving additional board
space and microcontroller I/O pins.
The MAX3110E/MAX3111E UART
includes an oscillator circuit derived from
an external crystal, and a baud-rate
generator with software-programmable
divider ratios for all common baud rates
from 300baud to 230kbaud. The UART
features an 8-word-deep receive FIFO that
minimizes processor overhead and
provides a flexible interrupt with four
maskable sources. One input and one output
control line are included for hardware
handshaking.
A proprietary low-dropout (LDO)
output stage allows the 2-driver/2-receiver
interface to deliver true RS-232 performance
down to VCC = 3V (4.5V for MAX3110E),
while drawing only 600µA. During shut-
The MAX3110E/MAX3111E are
available in 28-pin SO and DIP packages,
with prices starting from $4.73 (1000-up,
FOB USA).
True
RS-232
-pin S O
The MAX2235 is the first 900MHz,
1W silicon power amplifier (PA) to
feature an autoramping output capability.
During turn-on and turn-off, an external
capacitor causes the RF output to ramp up
and down gradually, thereby minimizing
unwanted output-transient noise and
spectral splatter found in FSK- and
TDMA-based ISM-band applications.
This unique feature is not available in
existing GaAs MESFET and HBT PAs.
The MAX2235 delivers 30.3dBm of
output power and 47% power-added efficiency while operating with a +3.6V
supply. A power-control pin lets you
adjust the gain over a 37dB range. The
The MAX2473 has a single opencollector output, plus a bias-control pin that
varies the output power as required to save
current. It adjusts the output power from
-10dBm to -2dBm while maintaining better
than -25dBc harmonic suppression.
Compared to discrete designs, each of these
monolithic buffer amps saves board space
by eliminating up to 15 components.
bias adjusts automatically to maintain
optimum efficiency, even at lower outputpower levels. To further decrease the
system cost and increase battery life, a
shutdown mode reduces the supply
current to <10µA without the need for a
supply switch.
The MAX2235 is designed for
constant-envelope applications such as
AMPS, 2-way pagers, and FSK-based
systems in the 868MHz/900MHz ISM
PROBLEM: Steep On/Off Slope
Causes Undesireable Transient
Noise and Spectral Splatter
band. Its single supply voltage (+2.7V to
+5.5V) eliminates the need for sequencing
circuitry and the negative bias required in
GaAs MESFET designs.
The MAX2235 is available in a
thermally enhanced 20-pin TSSOP-EP
(exposed paddle) package. Prices start
from $3.23 (1000-up, FOB USA). A fully
assembled evaluation kit (MAX2235
EVKIT) is available to help reduce design
time.
SOLUTION: Power Ramp Control
Provides Gradual On/Off Slope,
Set By One External Capacitor
LOW
Si B -COST
TEC iPOLAR
HNO
LOG
Y
OUTPUT POWER
900MHz, 1W
silicon PA reduces
output noise and
spectral splatter
OUTPUT POWER
28
The MAX2472/MAX2473 are lowcost, wideband, high-isolation buffer amplifiers offering the most functionality
available in a 6-pin SOT23 package. The
MAX2472 provides dual open-collector
outputs capable of delivering -5dBm while
maintaining better than -25dBc harmonic
suppression. Dual outputs are ideal for
simultaneously driving two mixers, or one
mixer and a PLL.
Both parts operate over a wide frequency range (500MHz to 2500MHz),
providing 12dB gain and greater than 40dB
isolation at 900MHz. High reverse isolation
and low supply current make them ideal for
high-performance, low-power applications.
Both operate from a single supply in the
+2.7V to +5.5V range and are available in
tiny, 6-pin SOT23 packages. Prices start
from $0.80 (1000-up, FOB USA).
SPI
µC
Wideband buffer
amps in SOT23-6
TIME
TIME
COMPETITION
MAX2235
23
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