MAX8891/MAX8892 High PSRR, Low-Dropout, 150mA Linear Regulators General Description

MAX8891/MAX8892 High PSRR, Low-Dropout, 150mA Linear Regulators General Description
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
General Description
The MAX8891/MAX8892 low-dropout (LDO) linear regulators are designed to deliver up to 150mA continuous
output current. These regulators achieve a low 120mV
dropout for 120mA load current.
The MAX8891 only requires an input/output capacitor,
hence achieving the smallest PCB area. The
MAX8892’s output voltage can be adjusted with an
external divider.
The MAX8891 is preset to a variety of voltages in the
1.5V to 4.5V range. Designed with a p-channel
MOSFET series pass transistor, the MAX8891/MAX8892
maintain very low ground current (40µA).
The regulators are designed and optimized to work with
low-value, low-cost ceramic capacitors. The MAX8891/
MAX8892 require only 1µF (typ) of output capacitance
for stability with any load. When disabled, current consumption drops to below 1µA.
These regulators are available in a tiny 5-pin SC70
package.
Applications
Cellular and Cordless Phones
PDA and Palmtop Computers
Base Stations
Bluetooth Portable Radios and Accessories
Wireless LANs
Digital Cameras
Personal Stereos
Portable and Battery-Powered Equipment
Features
♦
♦
♦
♦
♦
♦
♦
Space-Saving SC70 Package
65dB PSRR at 10kHz
120mV Dropout at 120mA Load
Stable with 1µF Ceramic Capacitor for Any Load
Guaranteed 150mA Output
Only Need Input and Output Capacitors (MAX8891)
Output Voltages: 1.5V, 1.8V, 2.5V, 2.6V, 2.7V, 2.8V,
2.85V, 3V, 3.3V, 4.5V (MAX8891) and Adjustable
(MAX8892)
♦ Low 40µA Ground Current
♦ Excellent Load/Line Transient
♦ Overcurrent and Thermal Protection
Ordering Information
TEMP RANGE
PIN-PACKAGE
MAX8891EXKxy+T
PART*
-40°C to +85°C
5 SC70
MAX8891EXKxy/V+T
-40°C to +85°C
5 SC70
MAX8892EXK+T
-40°C to +85°C
5 SC70
*xy is the output voltage code (see Output Voltage Selector
Guide). Other versions between 1.5V and 4.5V are available in
100mV increments. Contact factory for other versions.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Typical Operating Circuits
INPUT
2V TO 6V
IN
ON
OFF
OUTPUT PRESET
1.5V TO 4.5V
MAX8891
CIN = 1μF
Output Voltage Selector Guide appears at end of data sheet.
OUT
SHDN
COUT = 1μF
GND
Pin Configuration
TOP VIEW
+
GND 2
INPUT
2V TO 6V
5 OUT
IN 1
MAX8891/
MAX8892
CIN = 1μF
ON
OFF
4 N.C. (MAX8891)
FB (MAX8892)
SHDN 3
IN
OUT
MAX8892
OUTPUT ADJUSTABLE
1.5V TO 4.5V
R1
FB
SHDN
GND
COUT = 1μF
R2
SC70
For pricing, delivery, and ordering information, please contact Maxim Direct at
1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
19-4537; Rev 1; 12/11
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +7V
Output Short-Circuit Duration.....................................Continuous
OUT, SHDN to GND ....................................-0.3V to (VIN + 0.3V)
FB, BP, N.C. to GND ................................-0.3V to (VOUT + 0.3V)
Continuous Power Dissipation (TA = +70°C)
5-Pin SC70 (derate 3.1mW/°C above +70°C) ..............0.247W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
SC70
Junction-to-Ambient Thermal Resistance (θJA) .........324°C/W
Junction-to-Case Thermal Resistance (θJC) ..............115°C/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(VIN = VOUT + 0.5V, TA = -40°C to +85°C, unless otherwise noted. CIN = 1µF, COUT = 1µF. Typical values are at TA = +25°C; the
MAX8892 is tested with 2.45V output, unless otherwise noted.) (Note 2)
PARAMETER
Input Voltage Range
SYMBOL
CONDITIONS
VIN
Output Voltage Accuracy
I OUT
Current Limit
ILIM
TYP
2
I OUT = 100μA to 80mA
Maximum Output Current
MIN
-3
MAX
UNITS
6
V
+3
%
150
mA
I OUT = 90% of nominal value
200
mA
VOUT 3V, I OUT = 120mA
120
Dropout Voltage (Note 3)
2.5V VOUT < 3V, I OUT = 120mA
135
180
Ground Current
IQ
2V VOUT < 2.5V, I OUT = 120mA
I OUT = 0.05mA
40
μA
Line Regulation
VLNR
VIN = (VOUT + 0.5V) to 6V, I OUT = 0.1mA
0.001
%/V
Load Regulation
VLDR
I OUT = 1mA to 80mA
0.003
%/mA
Shutdown Supply Current
I SHDN
VSHDN = 0V
Ripple Rejection
PSRR
Output Noise Voltage (RMS)
f = 10kHz, I OUT = 10mA
f = 100Hz to 100kHz, ILOAD = 80mA
SHDN Logic-Low Level
VIN = 2V to 6V
SHDN Logic-High Level
VIN = 2V to 6V
SHDN Input Bias Current
VIN = 6V,
VSHDN = 0V or 6V
TA = +25°C
TA = +85°C
0.01
FB Input Bias Current
(MAX8892)
VIN = 6V,
VFB = 1.3V
TA = +25°C
0.006
TA = +85°C
0.01
Thermal Shutdown
Thermal-Shutdown Hysteresis
TA = +25°C
0.003
TA = +85°C
0.05
mV
1
μA
dB
65
μV
230
0.4
1.5
V
V
μA
0.1
μA
160
°C
10
°C
Note 2: Limits are 100% tested at TA = +25°C. Limits over operating temperature range are guaranteed by design.
Note 3: Dropout is defined as VIN - VOUT when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V.
2
Maxim Integrated
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Typical Operating Characteristics
(VIN = VOUT + 0.5V, CIN = 1µF, COUT = 1µF, TA = +25°C, unless otherwise noted.)
1.5
IOUT = 120mA
0.2
0
-0.2
0.5
-0.4
0.0
-0.6
MAX8891/2 toc03
IOUT = 1mA
0.8
0.6
% DEVIATION (%)
2.0
1.0
0.4
% DEVIATION (%)
IOUT = 0mA
1.0
MAX8891/2 toc02
2.5
OUTPUT VOLTAGE (V)
0.6
MAX8891/2 toc01
3.0
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
OUTPUT VOLTAGE vs. INPUT VOLTAGE
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
3
4
5
6
0
25
140
120
100
80
TA = -40°C
60
100
125
10
35
GROUND PIN CURRENT vs. INPUT VOLTAGE
200
150
100
300
250
200
150
100
IOUT = 0mA
50
20
0
25
50
75
100
125
0
2.0
150
2.2
2.8
3.0
3.2
0
VIN = 3.8V
150
100
75
100
Maxim Integrated
125
150
1000
70
60
40
50
40
30
35
20
ILOAD = 10mA
0
30
50
100
80
10
LOAD CURRENT (mA)
5
PSRR vs. FREQUENCY
MAX8891/2 toc08
45
50
0
4
3
90
PSRR (dB)
250
25
2
INPUT VOLTAGE (V)
50
GROUND PIN CURRENT (μA)
MAX8891/2 toc07
VIN = 5.5V
0
1
GROUND PIN CURRENT vs. TEMPERATURE
GROUND PIN CURRENT vs. LOAD CURRENT
350
200
2.6
OUTPUT (V)
LOAD CURRENT (mA)
300
2.4
MAX8891/2 toc09
0
85
350
50
0
60
TEMPERATURE (°C)
IOUT = 80mA
40
GROUND PIN CURRENT (μA)
-15
-40
150
250
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV))
TA = +85°C
MAX8891/2 toc04
TA = +25°C
160
75
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
DROPOUT VOLTAGE vs. LOAD CURRENT
200
180
50
LOAD CURRENT (mA)
MAX8891/2 toc06
2
INPUT VOLTAGE (V)
GROUND PIN CURRENT (μA)
1
MAX8891/2 toc05
0
-1.0
-40
-15
10
35
TEMPERATURE (°C)
60
85
0.01
0.1
1
10
FREQUENCY (kHz)
3
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Typical Operating Characteristics (continued)
(VIN = VOUT + 0.5V, CIN = 1µF, COUT = 1µF, TA = +25°C, unless otherwise noted.)
LOAD TRANSIENT RESPONSE
dl/dt = 0.5mA/μs
LOAD TRANSIENT RESPONSE
dl/dt = 5mA/μs
MAX8891/2 toc10
50mA
10mA
MAX8891/2 toc11
50mA
VIN = 3.5V
ILOAD
25mA/div
10mA
dl/dt = 0.5mA/μs
LOAD TRANSIENT RESPONSE
dl/dt = 20mA/μs
10mA
MAX8891/2 toc12
50mA
VIN = 3.5V
ILOAD
25mA/div
10mA
dl/dt = 0.5mA/μs
VIN = 3.5V
10mA
10mA
dl/dt = 20mA/μs
VIN
10mV/div
VIN
10mV/div
VIN
10mV/div
VOUT
10mV/div
VOUT
10mV/div
VOUT
10mV/div
200μs/div
20μs/div
4μs/div
STARTUP WAVEFORM
SHUTDOWN WAVEFORM
LINE TRANSIENT RESPONSE
dv/dt = 500mV/μs
MAX8891/2 toc13
VIN = 3.5V
RLOAD = 30Ω
ILOAD
25mA/div
MAX8891/2 toc15
MAX8891/2 toc14
VIN = 3.5V
RLOAD = 30Ω
ON
ON
VSHDN
2V/div
OFF
RLOAD = 30Ω
4V
VSHDN
2V/div
OFF
dv/dt = 500mV/μs
4V
VIN
500mV/div
3.5V
VOUT
500mV/div
VOUT
10mV/div
VOUT
500mV/div
10μs/div
40μs/div
40μs/div
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
LINE TRANSIENT RESPONSE
dv/dt = 200mV/μs
MAX8891/2 toc16
MAX8891/2 to17
100
RLOAD = 30Ω
5V
dv/dt = 200mV/μs
5V
VIN
1V/div
VOUT
10mV/div
COUT ESR (Ω)
3.5V
10
1
0.1
STABLE REGION
0.01
40μs/div
0
25
50
75
100
125
150
LOAD CURRENT (mA)
4
Maxim Integrated
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Pin Description
PIN
NAME
MAX8891
MAX8892
1
1
IN
2
2
GND
FUNCTION
Unregulated Input Supply
Ground
3
3
SHDN
—
4
FB
4
—
N.C.
Not Internally Connected
5
5
OUT
Regulated Output Voltage. Bypass with a capacitor to GND. See the Capacitor Selection
and Regulator Stability section for more details.
Shutdown. Pull low to disable the regulator.
Adjustable Output Feedback Point
Detailed Description
The MAX8891/MAX8892 are low-dropout, low-quiescent current linear regulators designed for spacerestricted applications. The parts are available with
preset output voltages ranging from 1.5V to 4.5V in
100mV increments. These devices can supply loads up
to 150mA. As shown in the Functional Diagram, the
MAX8891 consists of an innovative bandgap core, error
amplifier, p-channel pass transistor, and internal feedback voltage-divider. The MAX8892 allows for
adjustable output with an external feedback network.
Additional blocks include a current limiter, thermal sensor, and shutdown logic.
The 1.225V bandgap reference is connected to the
error amplifier’s inverting input. The error amplifier compares this reference with the feedback voltage and
amplifies the difference. If the feedback voltage is lower
than the reference voltage, the pass-transistor gate is
pulled low. This allows more current to pass to the output and increases the output voltage. If the feedback
voltage is too high, the pass transistor gate is pulled
high, allowing less current to pass to the output. The
output voltage is fed back through an internal (external
for the MAX8892) resistor voltage-divider connected to
the OUT pin.
Internal P-Channel Pass Transistor
The MAX8891/MAX8892 feature a 1Ω (typ) p-channel
MOSFET pass transistor. This provides several advantages over similar designs using a PNP pass transistor,
including longer battery life. The p-channel MOSFET
requires no base drive, which considerably reduces quiescent current. PNP-based regulators waste considerable current in dropout when the pass transistor
saturates. They also use high base-drive current under
Maxim Integrated
heavy loads. The MAX8891/MAX8892 do not suffer from
these problems and consume only 40µA of quiescent
current in light load and 220µA in dropout (see the
Typical Operating Characteristics).
Output Voltage Selection
The MAX8891 is supplied with factory-set output voltages from 1.5V to 4.5V, in 100mV increments (see the
Ordering Information). The MAX8892 features a useradjustable output through an external feedback network (see the Typical Operating Circuits).
To set the output of the MAX8892, use the following
equation:
⎛ VOUT ⎞
R1 = R2 × ⎜
-1
⎝ VREF ⎟⎠
where R2 is chosen to be less than 240kΩ and VREF =
1.225V. Use 1% or better resistors.
Shutdown
The MAX8891/MAX8892 feature a low-power shutdown
mode that reduces quiescent current less than 1µA.
Driving SHDN low disables the voltage reference, error
amplifier, gate-drive circuitry, and pass transistor (see
the Functional Diagram), and the device output enters a
high-impedance state. Connect SHDN to IN for normal
operation.
Current Limit
The MAX8891/MAX8892 include a current limiter, which
monitors and controls the pass transistor’s gate voltage, limiting the output current to 200mA. The output
can be continuously shorted to ground without damaging the part.
5
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation
in the MAX8891/MAX8892. When the junction temperature exceeds TJ = +160°C, the thermal sensor signals
the shutdown logic, turning off the pass transistor and
allowing the IC to cool down. The thermal sensor turns
the pass transistor on again after the IC’s junction temperature drops by 10°C, resulting in a pulsed output during continuous thermal-overload conditions.
Thermal-overload protection is designed to protect the
MAX8891/MAX8892 in the event of a fault condition. For
continual operation, do not exceed the absolute maximum junction temperature rating of TJ = +150°C.
Operating Region and Power Dissipation
The MAX8891/MAX8892 maximum power dissipation
depends on the thermal resistance of the case and circuit board, the temperature difference between the die
junction and ambient, and the rate of airflow. The power
dissipation across the device is:
P = IOUT (VIN - VOUT)
The maximum power dissipation is:
PMAX = (TJ - TA)/(θJC + θCA)
where TJ - TA is the temperature difference between the
MAX8891/MAX8892 die junction and the surrounding air,
θJC is the thermal resistance of the package, and θCA is
the thermal resistance through the PCB, copper traces,
and other materials to the surrounding air.
The GND pin of the MAX8891/MAX8892 performs the
dual function of providing an electrical connection to
ground and channeling heat away. Connect the GND
pin to ground using a large pad or ground plane.
6
Applications Information
Capacitor Selection
and Regulator Stability
Use a 1µF capacitor on the MAX8891/MAX8892 input
and a 1µF capacitor on the output. Larger input capacitor
values and lower ESRs provide better noise rejection and
line-transient response. Reduce output noise and
improve load-transient response, stability, and powersupply rejection by using large output capacitors. Note
that some ceramic dielectrics exhibit large capacitance
and ESR variation with temperature. With dielectrics such
as Z5U and Y5V, it may be necessary to use a 2.2µF or
larger output capacitor to ensure stability at temperatures
below -10°C. With X7R or X5R dielectrics, 1µF is sufficient
at all operating temperatures. A graph of the region of
stable COUT ESR vs. load current is shown in the Typical
Operating Characteristics.
PSRR and Transient Response
The MAX8891/MAX8892 are designed to deliver high
PSRR as well as low dropout and low quiescent currents
in battery-powered systems. The MAX8891/MAX8892
power-supply rejection is 65dB at 10kHz.
When operating from sources other than batteries,
improved supply-noise rejection and transient response
can be achieved by increasing the values of the input
and output bypass capacitors, and through passive filtering techniques. The Typical Operating Characteristics
show the MAX8891/MAX8892 line- and load-transient
responses.
Dropout Voltage
A regulator’s minimum dropout voltage determines the
lowest usable supply voltage. In battery-powered
systems, this determines the useful end-of-life battery
voltage. Because the MAX8891/MAX8892 use a
p-channel MOSFET pass transistor, their dropout voltage is a function of drain-to-source on-resistance
(RDS(ON)) multiplied by the load current (see the Typical
Operating Characteristics).
Maxim Integrated
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Functional Diagram
IN
SHDN
SHUTDOWN AND
POWER-ON CONTROL
ERROR
AMP
MAX8891/
MAX8892
MOS DRIVER
WITH ILIMIT
P
OUT
*
THERMAL
SENSOR
FB**
1.225V REFERENCE
*
GND
*MAX8891 ONLY
**MAX8892 ONLY
Chip Information
Output Voltage Selector Guide
PART
V OUT (V)
TOP MARK
PROCESS: BiCMOS
MAX8891EXK15+T
1.5
ATI
Package Information
MAX8891EXK18+T
1.8
ATJ
MAX8891EXK25+T
2.5
ATL
MAX8891EXK26+T
2.6
ATM
MAX8891EXK28+T
2.8
ATO
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
MAX8891EXK29+T
2.85
ATP
MAX8891EXK89+T
2.9
ATV
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
MAX8891EXK30+T
3.0
ATQ
5 SC70
X5+1
21-0076
90-0188
MAX8891EXK31+T
3.1
ATR
MAX8891EXK33+T
3.3
ATS
MAX8891EXK33/V+T
3.3
AUR
MAX8891EXK45+T
4.5
ATU
Adjustable
ATW
MAX8892EXK+T
Note: Standard output voltage options, shown in bold, are
available. Contact the factory for other output voltages between
1.5V and 4.5V. Minimum order quantity is 15,000 units.
Maxim Integrated
7
MAX8891/MAX8892
High PSRR, Low-Dropout, 150mA
Linear Regulators
Revision History
REVISION
NUMBER
REVISION
DATE
0
3/09
1
12/11
DESCRIPTION
Initial release
PAGES
CHANGED
—
Added the /V option to the Ordering Information table and the Output Voltage Selector
Guide; updated the Package Information table
1, 7
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
8
© 2011 Maxim Integrated Products, Inc.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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