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19-4537; Rev 0; 3/09
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 (40A). The regulators are designed and optimized to work with low-value, low-cost ceramic capacitors. The MAX8891/ MAX8892 require only 1F (typ) of output capacitance for stability with any load. When disabled, current consumption drops to below 1A. These regulators are available in a tiny 5-pin SC70 package. Space-Saving SC70 Package 65dB PSRR at 10kHz 120mV Dropout at 120mA Load Stable with 1F 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 40A Ground Current Excellent Load/Line Transient Overcurrent and Thermal Protection
Features
MAX8891/MAX8892
Ordering Information
PART* MAX8891EXKxy+T MAX8892EXK+T TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 5 SC70 5 SC70
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
*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.
Typical Operating Circuits
INPUT 2V TO 6V IN OUT OUTPUT PRESET 1.5V TO 4.5V
CIN = 1F
MAX8891
SHDN COUT = 1F
Output Voltage Selector Guide appears at end of data sheet.
ON OFF
Pin Configuration
TOP VIEW +
IN 1 5 OUT
INPUT 2V TO 6V IN
GND
OUT
OUTPUT ADJUSTABLE 1.5V TO 4.5V
GND 2
MAX8891/ MAX8892
4 N.C. (MAX8891) FB (MAX8892)
CIN = 1F ON OFF
MAX8892
SHDN FB
R1
COUT = 1F R2
SHDN 3
GND
SC70
________________________________________________________________ Maxim Integrated Products
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For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
High PSRR, Low-Dropout, 150mA Linear Regulators MAX8891/MAX8892
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +7V Output Short-Circuit Duration.....................................Continuous OUT, SHDN to GND ......................................-0.3V to (IN + 0.3V) FB, BP, N.C. to GND..................................-0.3V to (OUT + 0.3V) Continuous Power Dissipation (TA = +70C) 5-Pin SC70 (derate 3.1mW/C above +70C) ..............0.247W JA 5-Pin SC70 .................................................................324C/W Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
ELECTRICAL CHARACTERISTICS
(VIN = VOUT + 0.5V, TA = -40C to +85C, unless otherwise noted. CIN = 1F, COUT = 1F. Typical values are at TA = +25C; the MAX8892 is tested with 2.45V output, unless otherwise noted.) (Note 1)
PARAMETER Input Voltage Range Output Voltage Accuracy Maximum Output Current Current Limit Dropout Voltage (Note 2) Ground Current Line Regulation Load Regulation Shutdown Supply Current Ripple Rejection Output Noise Voltage (RMS) SHDN Logic-Low Level SHDN Logic-High Level SHDN Input Bias Current FB Input Bias Current (MAX8892) Thermal Shutdown Thermal-Shutdown Hysteresis IQ VLNR VLDR ISHDN PSRR IOUT ILIM OUT = 90% of nominal value VOUT 3V, IOUT = 120mA 2.5V VOUT < 3V, IOUT = 120mA 2V VOUT < 2.5V, IOUT = 120mA IOUT = 0.05mA VIN = (VOUT + 0.5V) to 6V, IOUT = 0.1mA IOUT = 1mA to 80mA SHDN = 0V TA = +25C TA = +85C SYMBOL VIN IOUT = 100A to 80mA CONDITIONS MIN 2 -3 150 200 120 135 180 40 0.001 0.003 0.003 0.05 65 230 0.4 1.5 TA = +25C TA = +85C TA = +25C TA = +85C 0.01 0.006 0.01 160 10 0.1 1 A %/V %/mA A dB V V V A A C C mV TYP MAX 6 +3 UNITS V % mA mA
f = 10kHz, IOUT = 10mA f = 100Hz to 100kHz, ILOAD = 80mA VIN = 2V to 6V VIN = 2V to 6V VIN = 6V, SHDN = 0V or 6V VIN = 6V, VFB = 1.3V
Note 1: Limits are 100% tested at TA = +25C. Limits over operating temperature range are guaranteed by design. Note 2: Dropout is defined as VIN - VOUT when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V.
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High PSRR, Low-Dropout, 150mA Linear Regulators
Typical Operating Characteristics
(VIN = VOUT + 0.5V, CIN = 1F, COUT = 1F, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT
MAX8891/2 toc01 MAX8891/2 toc02
MAX8891/MAX8892
OUTPUT VOLTAGE vs. INPUT VOLTAGE
3.0 2.5 OUTPUT VOLTAGE (V) IOUT = 0mA 2.0 1.5 1.0 0.5 0.0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) IOUT = 120mA 0.6 0.4 % DEVIATION (%) 0.2 0 -0.2 -0.4 -0.6 0
OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE
0.8 0.6 % DEVIATION (%) 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 IOUT = 1mA
MAX8891/2 toc03
1.0
25
50
75
100
125
150
-40
-15
10
35
60
85
LOAD CURRENT (mA)
TEMPERATURE (C)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8891/2 toc04
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
MAX8891/2 toc05
GROUND PIN CURRENT vs. INPUT VOLTAGE
MAX8891/2 toc06
200 180 DROPOUT VOLTAGE (mV)) 160 140 120 100 80 60 40 20 0 0 25 50 75 100 125 TA = -40C TA = +25C TA = +85C
250 IOUT = 80mA DROPOUT VOLTAGE (mV) 200
350 300 GROUND PIN CURRENT (A) 250 200 150 100 50 IOUT = 0mA
150
100
50
0 150 2.0 2.2 2.4 2.6 2.8 3.0 3.2 LOAD CURRENT (mA) OUTPUT (V)
0 0 1 2 3 4 5 INPUT VOLTAGE (V)
GROUND PIN CURRENT vs. LOAD CURRENT
MAX8891/2 toc07
GROUND PIN CURRENT vs. TEMPERATURE
MAX8891/2 toc08
PSRR vs. FREQUENCY
80 70 60 PSRR (dB) 50 40 30
MAX8891/2 toc09
350 300 GROUND PIN CURRENT (A) 250 200 150 100 50 0 0 25 50 75 100 125 VIN = 3.8V VIN = 5.5V
50
90
GROUND PIN CURRENT (A)
45
40
35
20 10 ILOAD = 10mA 0.01 0.1 1 10 100 1000
30 150 -40 -15 10 35 60 85 LOAD CURRENT (mA) TEMPERATURE (C)
0 FREQUENCY (kHz)
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High PSRR, Low-Dropout, 150mA Linear Regulators MAX8891/MAX8892
Typical Operating Characteristics (continued)
(VIN = VOUT + 0.5V, CIN = 1F, COUT = 1F, TA = +25C, unless otherwise noted.)
LOAD TRANSIENT RESPONSE dl/dt = 0.5mA/s
MAX8891/2 toc10
LOAD TRANSIENT RESPONSE dl/dt = 5mA/s
MAX8891/2 toc11
LOAD TRANSIENT RESPONSE dl/dt = 20mA/s
MAX8891/2 toc12
50mA
VIN = 3.5V 10mA ILOAD 25mA/div 10mA
50mA
VIN = 3.5V 10mA ILOAD 25mA/div 10mA
50mA
VIN = 3.5V 10mA ILOAD 25mA/div
10mA
dl/dt = 0.5mA/s
dl/dt = 0.5mA/s
dl/dt = 20mA/s VIN 10mV/div VIN 10mV/div
VIN 10mV/div
VOUT 10mV/div 200s/div 20s/div
VOUT 10mV/div 4s/div
VOUT 10mV/div
STARTUP WAVEFORM
MAX8891/2 toc13
SHUTDOWN WAVEFORM
MAX8891/2 toc14
LINE TRANSIENT RESPONSE dv/dt = 500mV/s
MAX8891/2 toc15
VIN = 3.5V RLOAD = 30
ON VSHDN 2V/div
ON
VIN = 3.5V RLOAD = 30 OFF VSHDN 2V/div 4V
RLOAD = 30 dv/dt = 500mV/s 4V VIN 500mV/div 3.5V
OFF
VOUT 500mV/div
VOUT 500mV/div
VOUT 10mV/div
10s/div
40s/div
40s/div
LINE TRANSIENT RESPONSE dv/dt = 200mV/s
MAX8891/2 toc16
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX8891/2 to17
100
RLOAD = 30 5V dv/dt = 200mV/s 5V VIN 1V/div 3.5V VOUT 10mV/div COUT ESR () 10
1
0.1 STABLE REGION 0.01 40s/div 0 25 50 75 100 125 150 LOAD CURRENT (mA)
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High PSRR, Low-Dropout, 150mA Linear Regulators
Pin Description
PIN MAX8891 1 2 3 -- 4 5 MAX8892 1 2 3 4 -- 5 NAME IN GND SHDN FB N.C. OUT Unregulated Input Supply Ground Shutdown. Pull low to disable the regulator. Adjustable Output Feedback Point Not Internally Connected Regulated Output Voltage. Bypass with a capacitor to GND. See the Capacitor Selection and Regulator Stability section for more details. FUNCTION
MAX8891/MAX8892
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.
heavy loads. The MAX8891/MAX8892 do not suffer from these problems and consume only 40A of quiescent current in light load and 220A 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 - 1 R1 = R2 X VREF where R2 is chosen to be less than 240k 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 1A. 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.
Internal P-Channel Pass Transistor
The MAX8891/MAX8892 feature a 1 (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
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.
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High PSRR, Low-Dropout, 150mA Linear Regulators MAX8891/MAX8892
Thermal-Overload Protection
Thermal-overload protection limits total power dissipation in the MAX8891/MAX8892. When the junction temperature exceeds TJ = +160C, 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 10C, 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 = +150C.
Applications Information
Capacitor Selection and Regulator Stability
Use a 1F capacitor on the MAX8891/MAX8892 input and a 1F 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 2.2F or larger output capacitor to ensure stability at temperatures below -10C. With X7R or X5R dielectrics, 1F 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.
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)/(JC + CA) where TJ - TA is the temperature difference between the MAX8891/MAX8892 die junction and the surrounding air, JC is the thermal resistance of the package, and CA 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.
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).
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High PSRR, Low-Dropout, 150mA Linear Regulators
Functional Diagram
MAX8891/MAX8892
IN
SHDN
SHUTDOWN AND POWER-ON CONTROL ERROR AMP MOS DRIVER WITH ILIMIT
MAX8891/ MAX8892
P OUT *
THERMAL SENSOR
1.225V REFERENCE *
FB**
GND
*MAX8891 ONLY **MAX8892 ONLY
Output Voltage Selector Guide
PART MAX8891EXK15+T MAX8891EXK18+T MAX8891EXK25+T MAX8891EXK26+T MAX8891EXK28+T MAX8891EXK29+T MAX8891EXK89+T MAX8891EXK31+T MAX8891EXK33+T MAX8891EXK45+T MAX8892EXK+T VOUT (V) 1.5 1.8 2.5 2.6 2.8 2.85 2.9 3.1 3.3 4.5 Adjustable TOP MARK ATI ATJ ATL ATM ATO ATP ATV ATR ATS ATU ATW
Chip Information
PROCESS: BiCMOS
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.
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High PSRR, Low-Dropout, 150mA Linear Regulators MAX8891/MAX8892
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 5 SC70 PACKAGE CODE X5-1 DOCUMENT NO. 21-0076
PACKAGE OUTLINE, 5L SC70
21-0076
E
1 1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
SC70, 5L.EPS

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