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19-1556; Rev 0; 10/99
150mA, Low-Dropout Linear Regulator with Power-OK Output
General Description
The MAX8875 low-dropout linear regulator operates from a +2.5V to +6.5V input range and delivers up to 150mA. A P-channel MOSFET pass transistor allows its 85A supply current to remain independent of the load, making this device ideal for battery-operated portable equipment such as PCS phones, cellular phones, cordless phones, and modems. The MAX8875 features a power-OK output that indicates when the output is out of regulation. The device is available in several preset output voltage versions: 5.0V, 3.3V, 3.0V, 2.7V, or 2.5V. Other features include 1A (max) shutdown current, short-circuit protection, thermal shutdown protection, and reverse-battery protection. The device comes in a miniature 5-pin SOT23 package. The MAX8875 is optimized for use with a 1F ceramic output capacitor. For a pin-compatible, functionally equivalent device for use with a higher ESR output capacitor, see the MAX8885 data sheet. o Power-OK Output o Small Output Capacitor (1F ceramic) o Preset Output Voltages (1% accuracy) o Guaranteed 150mA Output Current o 85A No-Load Supply Current o Low 110mV Dropout at 100mA Load (165mV at 150mA load) o Thermal-Overload and Short-Circuit Protection o Reverse-Battery Protection o 60dB PSRR at 100Hz o 1A max Shutdown Current
Features
MAX8875
Applications
PCS Telephones Cellular Telephones Cordless Telephones PCMCIA Cards Hand-Held Instruments Palmtop Computers Electronic Planners Modems
PART MAX8875EUK25-T MAX8875EUK27-T MAX8875EUK30-T MAX8875EUK33-T MAX8875EUK50-T
Ordering Information
TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5
Output Voltage Selector Guide
PART MAX8875EUK25 MAX8875EUK27 MAX8875EUK30 MAX8875EUK33 VOUT (V) 2.5 2.7 3.0 3.3 TOP MARK ADKZ ADLA ADLB ADLC
Note: See Output Voltage Selector Guide for more information.
MAX8875EUK50 5.0 ADLD Note: Other output voltages between 2.5V and 5.0V are available in 100mV increments--contact the factory for information. Minimum order quantity is 25,000 units.
Typical Operating Circuit
OUTPUT PRESET 2.5V TO 5.0V 150mA COUT 1F
Pin Configuration
TOP VIEW
IN 1 5 OUT
INPUT +2.5V TO +6.5V IN CIN 1F OUT
GND 2
MAX8875
ON OFF 4 POK
MAX8875
100k SHDN GND POK TO C
SHDN 3
SOT23-5 ________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8875
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, POK to GND...............................................-7V to +7V SHDN to IN ...............................................................-7V to +0.3V OUT to GND ................................................-0.3V to (VIN + 0.3V) Output Short-Circuit Duration ........................................Indefinite Continuous Power Dissipation (TA = +70C) 5-Pin SOT23 (derate 7.1mW/C above +70C)..........571mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C JA ...............................................................................+140C/W 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(NOMINAL) + 1V, SHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER Input Voltage SYMBOL VIN TA = +25C, IOUT = 100A Output Voltage Accuracy IOUT = 100A TA = -40C to +85C IOUT ILIM IQ IOUT = 100A IOUT = 150mA IOUT = 100A Dropout Voltage (Note 2) VIN - VOUT IOUT = 50mA IOUT = 100mA IOUT = 150mA Line Regulation Load Regulation Output Voltage Noise Output Voltage AC PowerSupply Rejection Ratio SHUTDOWN Shutdown Supply Current SHDN Input Threshold SHDN Input Bias Current POWER-OK OUTPUT (1 - VOUT / VOUT(NOMINAL) 100, IOUT = 0, VOUT falling In dropout, VOUT falling Hysteresis, IOUT = 0 -3 -5 -5.3 1 -8 % IOFF VIH VIL ISHDN SHDN = GND VIN = 2.5V to 5.5V SHDN = IN or GND TA = +25C TA = +85C TA = +25C TA = +85C 2.0 0.4 0 0.05 100 0.005 0.02 1 A V nA PSRR VLNR VLDR VIN = (VOUT + 0.1V) to 6.5V, IOUT = 1mA IOUT = 100A to 120mA, COUT = 1F COUT = 10F, f = 10Hz to 100kHz f = 100Hz -0.15 IOUT = 100A to 120mA CONDITIONS MIN 2.5 -1.0 -2 -3 150 160 390 85 100 0.1 50 110 165 0 0.01 170 60 0.15 %/V %/mA VRMS dB 220 mV 180 TYP MAX 6.5 1.0 2 2 mA mA A % UNITS V
Maximum Output Current Current Limit Ground Pin Current
Power-OK Voltage Threshold
VPOK
2
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150mA, Low-Dropout Linear Regulator with Power-OK Output
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(NOMINAL) + 1V, SHDN = IN, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1) PARAMETER POK Output Voltage Low POK Output Leakage Current THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN TSHDN 170 20 C C SYMBOL VOL ISINK = 1mA 0 VPOK 6.5V, VOUT in regulation CONDITIONS MIN TYP MAX 0.4 1 UNITS V A
MAX8875
Note 1: Limits are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) methods. Note 2: Dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V.
Typical Operating Characteristics
(MAX8875EUK30, VIN = +3.6V, CIN = COUT = 1F, SHDN = IN, TA = +25C, unless otherwise noted.)
GROUND PIN CURRENT vs. INPUT VOLTAGE
MAX8875toc01
GROUND PIN CURRENT vs. OUTPUT LOAD
MAX8875toc02
GROUND PIN CURRENT vs. OUTPUT LOAD
VIN = VOUT(NOMINAL) + 0.5V 115 GROUND PIN CURRENT (A) 110 105 100 95 90 85 VOUT = 3.0V MAX8875EUK30 VOUT = 5.0V MAX8875EUK50
MAX8875toc03 MAX8875toc06
120 IOUT = 150mA GROUND PIN CURRENT (A) 100 80 60 40 20 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) IOUT = 0
115 110 VIN = 5.0V 105 100 VIN = 3.5V 95 90 85 0
120
GROUND PIN CURRENT (A)
15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA)
0
15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA)
GROUND PIN CURRENT vs. TEMPERATURE
130 120 GROUND PIN CURRENT (A) 110 100 90 80 70 60 -40 -15 10 35 60 85 TEMPERATURE (C) VIN = 3.6V IOUT = 150mA VIN = 3.6V OR 5.0V IOUT = 0 VIN = 5.0V IOUT = 150mA
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8875toc05
OUTPUT VOLTAGE vs. OUTPUT LOAD
3.10
3.5 3.0 OUTPUT VOLTAGE (V) 2.5 2.0 IOUT = 150mA 1.5 1.0 0.5 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) IOUT = 0
OUTPUT VOLTAGE (V)
3.05
3.00
VIN = 3.6V
2.95 VIN = 5.0V 2.90 0 15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA)
_______________________________________________________________________________________
3
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8875
Typical Operating Characteristics (continued)
(MAX8875EUK30, VIN = +3.6V, CIN = COUT = 1F, SHDN = IN, TA = +25C, unless otherwise noted.)
DROPOUT VOLTAGE vs. OUTPUT LOAD
MAX8875toc08 MAX8875toc07
OUTPUT VOLTAGE vs. TEMPERATURE
3.10 250
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX8875toc09
70 60 50 PSRR (dB)
OUTPUT VOLTAGE (V)
3.05
DROPOUT VOLTAGE (mV)
VIN = 3.6V OR 5.0V IOUT = 0
200
150
COUT = 10F TA = +85C TA = +25C 40 30 COUT = 1F 20 TA = -40C
3.00 VIN = 3.6V IOUT = 150mA 2.95 VIN = 5.0V IOUT = 150mA -40 -15 10 35 60 85 TEMPERATURE (C)
100
50
10 0 0.01
2.90
0 0 15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA)
0.1
1
10
100
1000
FREQUENCY (kHz)
OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
OUTPUT NOISE SPECTRAL DENSITY (V/Hz)
MAX8875toc10
OUTPUT NOISE
MAX8875toc11
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX8875toc12
10 COUT = 10F IOUT = 50mA
100
f = 10Hz TO 100kHz COUT = 10F IOUT = 50mA VOUT 500V/div
10 COUT ESR () 1
COUT = 10F
1 COUT = 1F STABLE REGION 0.1
0.1
0.01 0.1 1 10 100 10ms/div FREQUENCY (kHz)
0.01 1 30 60 90 120 150 LOAD CURRENT (mA)
LINE-TRANSIENT RESPONSE
MAX8875toc13
LOAD-TRANSIENT RESPONSE
MAX8875toc14
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX8875toc15
3.01V VOUT 3.00V 2.99V
VIN
5V 4V
3.01V VOUT ILOAD 3.00V 2.99V
3.02V VOUT 3.00V 2.98V 10s/div IOUT = 50mA ILOAD
50mA
50mA
0 10s/div VIN = VOUT + 0.5V, IOUT = 0 TO 50mA
0 10s/div VIN = VOUT + 0.1V, IOUT = 0 TO 50mA
4
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150mA, Low-Dropout Linear Regulator with Power-OK Output
Typical Operating Characteristics (continued)
(MAX8875EUK30, VIN = +3.6V, CIN = COUT = 1F, SHDN = IN, TA = +25C, unless otherwise noted.)
MAX8875
SHUTDOWN DELAY
MAX8875toc16
POK OUTPUT
MAX8875toc17
3V
VOUT 1V/div 0 2V VSHDN 1V/div 0
0
VOUT 2V/div VPOK 2V/div
0 4V 3V 2V 100s/div MAX8875EUK30, ROUT = 60 RPOK = 100k 200s/div
VIN 1V/div
POK STARTUP RESPONSE
MAX8875toc18
POK AND SHUTDOWN RESPONSE
VIN 2.5V/div
MAX8875toc19
5.0V
2V 0
VSHDN 2V/div
0 2.5V 0 5.0V VPOK 2.5V/div 0 10ms/div RPOK = 100k VOUT 2.5V/div
2V 0 4V
VOUT 2V/div
VPOK 2V/div 0 RLOAD = 60 10s/div RPOK = 100k
Pin Description
PIN 1 2 3 4 5 NAME IN GND SHDN POK OUT FUNCTION Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with 1F to GND (see the Capacitor Selection and Regulator Stability section). Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground plane to maximize power dissipation. Active-Low Shutdown Input. A logic low reduces the supply current to below 1A. Connect to IN for normal operation. Power-OK Output. Active-low, open-drain output indicates an out-of-regulation condition. Connect a 100k pull-up resistor to OUT for logic levels. If not used, leave this pin unconnected. Regulator Output. Fixed 5.0V, 3.3V, 3.0V, 2.7V, or 2.5V output. Sources up to 150mA. Bypass with 1F (<0.2 typical ESR) ceramic capacitor to GND. _______________________________________________________________________________________ 5
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8875
IN SHDN REVERSEBATTERY PROTECTION
ERROR AMP SHUTDOWN LOGIC
MOS DRIVER WITH ILIMIT
P
OUT
MAX8875
POK THERMAL SENSOR 1.25V REF 95% REF POK
GND
Figure 1. Functional Diagram
_______________Detailed Description
The MAX8875 is a low-dropout, low-quiescent-current linear regulator designed primarily for battery-powered applications. The device supplies loads up to 150mA and is available with preset output voltages of 2.5V, 2.7V, 3.0V, 3.3V, or 5.0V. As illustrated in Figure 1, the MAX8875 consists of a 1.25V reference, error amplifier, P-channel pass transistor, power-OK comparator, and internal feedback voltage divider. The 1.25V 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 lower, which 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 up, allowing less current to pass to the output. The output voltage feeds back through an internal resistor voltage divider connected to the OUT pin. Additional blocks include a current limiter, reversebattery protection, thermal sensor, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX8875 features a 1.1 (typ) P-channel MOSFET pass transistor. This provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current significantly. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The MAX8875 does not suffer from these problems and consumes only 100A of quiescent current whether in dropout, light-load, or heavy-load applications (see Typical Operating Characteristics).
Power-OK Output
When the output voltage goes out of regulation--as during dropout, current limit, or thermal shutdown--POK goes low. POK is an open-drain N-channel MOSFET. To obtain a logic-level output, connect a pull-up resistor from POK to OUT. To minimize current consumption, make this resistor as large as practical. A 100k resistor works well for most applications. A capacitor to GND may be added to generate a power-on-reset (POR) delay. The POK function is not active during shutdown. POK also provides a power-on-reset function that can operate down to VIN 1V. See POK Startup Response in the Typical Operating Characteristics.
Output Voltage
The MAX8875 is supplied with factory-set output voltages of 2.5V, 2.7V, 3.0V, 3.3V, or 5.0V. The part number's two-digit suffix identifies the nominal output voltage. For example, the MAX8875EUK33 has a preset output voltage of 3.3V (see Output Voltage Selector Guide).
6
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150mA, Low-Dropout Linear Regulator with Power-OK Output
Current Limit
The MAX8875 includes a current limiter that monitors and controls the pass transistor's gate voltage, limiting the output current to 390mA (typ). For design purposes, consider the current limit to be 160mA min to 600mA max. The output can be shorted to ground for an indefinite period of time without damaging the part.
__________Applications Information
Capacitor Selection and Regulator Stability
For stable operation over the full temperature range and with load currents up to 150mA, use a 1F (min) ceramic output capacitor with an ESR <0.2. To reduce noise and improve load-transient response, stability, and power-supply rejection, use large output capacitor values, such as 10F. 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 2.2F or more to ensure stability at temperatures below TA = -10C. With X7R or X5R dielectrics, 1F should be sufficient at all operating temperatures. Also, for high-ESR tantalum capacitors, 2.2F or more and a larger case size may be needed to maintain ESR in the stable region. For a pin-compatible, functionally equivalent device for use with a higher ESR output capacitor, see the MAX8885. A graph of the Region of Stable COUT ESR vs. Load Current is shown in the Typical Operating Characteristics.
MAX8875
Thermal-Overload Protection
When the junction temperature exceeds TJ = +170C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool. The thermal sensor will turn the pass transistor on again after the IC's junction temperature cools by 20C, resulting in a pulsed output during continuous thermal-overload conditions.Thermal-overload protection is designed to protect the MAX8875 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150C.
Operating Region and Power Dissipation
The MAX8875's maximum power dissipation depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipation across the device is P = IOUT (VIN - VOUT). The maximum power dissipation is: PMAX = (TJ - TA) / (JB + BA) where TJ - TA is the temperature difference between the MAX8875 die junction and the surrounding air, JB (or JC) is the thermal resistance of the package, and BA is the thermal resistance through the printed circuit board, copper traces, and other materials to the surrounding air. The MAX8875's ground pin (GND) performs the dual function of providing an electrical connection to system ground and channeling heat away. Connect GND to the system ground using a large pad or ground plane.
PSRR and Operation from Sources Other than Batteries
The MAX8875 is designed to deliver low dropout voltages and low quiescent currents in battery-powered systems. Power-supply rejection is 60dB at low frequencies. See the Power-Supply Rejection Ratio vs. Frequency graph in the Typical Operating Characteristics. Improve supply-noise rejection and transient response by increasing the values of the input and output bypass capacitors. The Typical Operating Characteristics show the MAX8875's line- and load-transient responses.
Dropout Voltage
A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the MAX8875 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-to-source on-resistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics): VDROPOUT = VIN - VOUT = RDS(ON) * IOUT
Reverse-Battery Protection
The MAX8875 has a unique protection scheme that limits the reverse supply current to 1mA when either VIN or V SHDN falls below ground. The circuitry monitors the polarity of these two pins and disconnects the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents device damage.
Chip Information
TRANSISTOR COUNT: 266
_______________________________________________________________________________________
7
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8875
Package Information
SOT5L.EPS
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) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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