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19-1576; Rev 0; 10/99
150mA, Low-Dropout Linear Regulator with Power-OK Output
General Description
The MAX8885 low-dropout (LDO) linear regulator operates from a +2.5V to +6.5V input voltage range and delivers up to 150mA. It uses a P-channel MOSFET pass transistor to allow a low 85A supply current--which is independent of the load--as well as LDO voltage. The MAX8885 is optimized to operate with low-cost, high-ESR output capacitors such as small case-size tantalum capacitors. It is ideal for cost-sensitive portable equipment such as PCS and cellular phones. For a pin-compatible, functionally equivalent device for use with a low-ESR, ceramic output capacitor, refer to the MAX8875 data sheet. The MAX8885 features a power-OK output that indicates when the output is out of regulation, and is available in preset output voltage versions of 5.0V, 3.3V, 3.0V, 2.7V, and 2.5V. Other features include 1A (max) shutdown current, short-circuit protection, thermal shutdown protection, and reverse-battery protection. The MAX8885 is available in a miniature 5-pin SOT23 package. o Pin Compatible with MIC5206 o Undervoltage Power-OK Output 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
o Optimized for Low-Cost Tantalum Capacitors
MAX8885
Applications
PCS Phones Cellular Phones Cordless Phones PCMCIA Cards Modems Hand-Held Instruments Palmtop Computers Electronic Planners
PART MAX8885EUK25 MAX8885EUK27 MAX8885EUK30 MAX8885EUK33 MAX8885EUK50
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 MAX8885EUK25 MAX8885EUK27 MAX8885EUK30 MAX8885EUK33 VOUT (V) 2.5 2.7 3.0 3.3 TOP MARK ADLE ADLF ADLG ADLH
Note: See Output Voltage Selector Guide for more information.
MAX8885EUK50 5.0 ADLJ Note: Other output voltages between 2.5V and 5.0V are available in 100mV increments--contact factory for information. Minimum order quantity is 25,000 units.
Typical Operating Circuit
OUTPUT PRESET 2.5V TO 5.0V 150mA COUT 4.7F
Pin Configuration
TOP VIEW
IN 1 5 OUT INPUT +2.5V TO +6.5V IN CIN 1F OUT
GND 2
MAX8885
ON OFF
MAX8885
100k SHDN GND POK TO C
SHDN 3
4
POK
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 MAX8885
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 TA = -40C to +85C, IOUT = 100A TA = -40C to +85C, IOUT = 100A to 120mA Maximum Output Current Current Limit Ground Pin Current IOUT ILIM IQ IOUT = 100A IOUT = 150mA IOUT = 100A Dropout Voltage (Note 2) VIN VOUT VLNR VLDR 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 IOFF VIH VIL I SHDN SHDN = GND VIN = 2.5V to 5.5V V SHDN = 5.5V 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 VIN = (VOUT + 0.1V) to 6.5V, IOUT = 1mA IOUT = 100A to 120mA, COUT = 4.7F COUT = 10F, f = 10Hz to 100kHz f = 100Hz -0.15 CONDITIONS MIN 2.5 -1 -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 2 2 mA mA A % UNITS V
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 POWER-OK OUTPUT (1 - VOUT / VOUT(NOMINAL))100, VOUT falling, IOUT = 0 In dropout, VOUT falling Hysteresis, IOUT = 0 POK Output Voltage Low POK Output Leakage Current THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN TSHDN 170 20 C C VOL ISINK = 1mA 0 VPOK 6.5V, VOUT in regulation -3 -5 -5.3 1 0.4 1 V A -8 % SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX8885
Power-OK Voltage Threshold
VPOK
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
(MAX8885EUK30, VIN = +3.6V, CIN = 1F, COUT = 4.7F, SHDN = IN, TA = +25C, unless otherwise noted.)
GROUND PIN CURRENT vs. INPUT VOLTAGE
MAX8885toc01
GROUND PIN CURRENT vs. OUTPUT LOAD
MAX8885toc02
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 MAX8885EUK30 VOUT = 5.0V MAX8885EUK50
MAX8885toc03
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)
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3
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8885
Typical Operating Characteristics (continued)
(MAX8885EUK30, VIN = +3.6V, CIN = 1F, COUT = 4.7F, SHDN = IN, TA = +25C, unless otherwise noted.)
GROUND PIN CURRENT vs. TEMPERATURE
MAX8885toc04
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8885toc05
OUTPUT VOLTAGE vs. OUTPUT LOAD
MAX8885toc06
130 120 GROUND PIN CURRENT (A) 110 100 90 80 70 60 -40 -15 10 35 60 VIN = 3.6V IOUT = 150mA VIN = 3.6V OR 5.0V IOUT = 0 VIN = 5.0V IOUT = 150mA
3.5 3.0 OUTPUT VOLTAGE (V) 2.5 2.0 IOUT = 150mA 1.5 1.0 0.5 0 IOUT = 0
3.10
OUTPUT VOLTAGE (V)
3.05
3.00
VIN = 3.6V
2.95 VIN = 5.0V 2.90 0 1 2 3 4 5 6 0 INPUT VOLTAGE (V) 15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA)
85
TEMPERATURE (C)
OUTPUT VOLTAGE vs. TEMPERATURE
MAX8885toc07
DROPOUT VOLTAGE vs. OUTPUT LOAD
MAX8885toc08
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
60 55 ROUT = 60
MAX8885toc09
130 120 OUTPUT VOLTAGE (V) 110 100 90 80 70 60 -40 -15 10 35 60 VIN = 5.0V IOUT = 150mA VIN = 3.6V IOUT = 150mA VIN = 3.6V OR 5.0V IOUT = 0
250
65
200 DROPOUT VOLTAGE (mV) TA = +85C
50 PSRR (dB) 45 40 35 COUT = 10F
150 TA = +25C
100
50
TA = -40C
30 25 COUT = 1F 0.1 1 10 100 1000 FREQUENCY (kHz)
0 85 0 15 30 45 60 75 90 105 120 135 150 OUTPUT LOAD (mA) TEMPERATURE (C)
20 0.01
OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY
MAX8885toc10
OUTPUT NOISE (10Hz TO 100kHz)
MAX8885toc11
REGION OF STABLE COUT ESR vs. LOAD CURRENT
MAX8885toc12
10 OUTPUT NOISE SPECTRAL DENSITY (V/Hz)
1000
100 VOUT 500V/div COUT = 1F 0.1 1 COUT = 10F 0.01 IOUT = 50mA 0.1 1 10 FREQUENCY (kHz) 100 1000 COUT = 10F ILOAD = 50mA 10ms/div COUT ESR () 1
10 STABLE REGION: COUT = 4.7F TO 10F
0.1 1 30 60 90 120 150 LOAD CURRENT (mA)
4
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150mA, Low-Dropout Linear Regulator with Power-OK Output
Typical Operating Characteristics (continued)
(MAX8885EUK30, VIN = +3.6V, CIN = 1F, COUT = 4.7F, SHDN = IN, TA = +25C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX8885toc15
MAX8885
LINE-TRANSIENT RESPONSE
MAX8885toc13
LOAD-TRANSIENT RESPONSE
MAX8885toc14
5V VIN 4V
50mA ILOAD 25mA/div 0
50mA ILOAD 25mA/div 0
3.02V VOUT 3.00V 2.98V ROUT = 60 100s/div
3.05V
VOUT 25mV/div
3.05V
VOUT 25mV/div VIN = VOUT + 0.1V CIN = 1F 5s/div
3.0V
VIN = VOUT + 0.5V CIN = 1F 5s/div
3.0V
SHUTDOWN DELAY
MAX8885toc16
POK OUTPUT
MAX8885toc17
POK STARTUP RESPONSE
5V VOUT 2V/div VPOK 2V/div 2.5V 0 2.5V 0 5V VIN 1V/div 2.5V 0 VPOK 2.5V/div
MAX8885toc18
3V VOUT 1V/div 0 2V VSHDN 1V/div 0 RLOAD = 60 100s/div 200s/div 0
VIN 2.5V/div VOUT 2.5V/div
0 4V 3V 2V
10ms/div
POK AND SHUTDOWN RESPONSE
MAX8885toc19
2V 0 2V 0 4V 2V 0 RLOAD = 60 10s/div
VSHDN
VOUT
VPOK
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5
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8885
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 capacitor to GND (see Capacitor Selection and Regulator Stability). 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 4.7F (>0.5 typ ESR) tantalum capacitor to GND.
Detailed Description
The MAX8885 is a low-dropout, low-quiescent-current linear regulator designed primarily for battery-powered applications using low-cost, high-ESR tantalum capacitors. The device delivers up to 150mA and is available with preset output voltages of 2.5V, 2.7V, 3.0V, 3.3V, or 5.0V. The MAX8885 consists of a 1.25V reference, error amplifier, P-channel pass transistor, power-OK comparator, and internal feedback voltage divider (Figure 1). 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 is fed back through an internal resistor voltage divider connected to the OUT pin. Additional blocks include a current limiter, reverse-battery protection, thermal sensor, and shutdown logic.
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 MAX8885 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 (POK)
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. The POK function is not active during shutdown. A capacitor to GND may be added to generate a power-on-reset (POR) delay, which can operate down to V IN 1V. (See POK Startup Response in the Typical Operating Circuit.)
Output Voltage
The MAX8885 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 MAX8885EUK33 indicates a preset output voltage of 3.3V (see Output Voltage Selector Guide).
Current Limit
The MAX8885 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.
Internal P-Channel Pass Transistor
The MAX8885 features a 1.1 (typ) P-channel MOSFET pass transistor. This provides several advantages over
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
6
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150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8885
IN SHDN REVERSE BATTERY PROTECTION
ERROR AMP SHUTDOWN LOGIC
MOS DRIVER WITH ILIMIT
P
OUT
MAX8885
POK THERMAL SENSOR 1.25V REF 95% REF POK
GND
Figure 1. Functional Diagram
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 thermaloverload conditions. Thermal-overload protection is designed to protect the MAX8885 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150C.
Reverse-Battery Protection
The MAX8885 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.
Applications Information
Capacitor Selection and Regulator Stability
The MAX8885 is designed primarily for applications using low-cost, high-ESR output capacitors such as small case-size tantalum electrolytic capacitors. These capacitors have ESR that can extend as high as 10, and their capacitance and ESR can vary widely over their operating temperature range. For stable operation over the full operating range, use a 4.7F (1F min) capacitor with ESR > 0.5 (see the Region of Stable C OUT ESR vs. Load Current graph in the Typical Operating Characteristics). Ceramic output capacitors should not be used with the MAX8885. For a pin-compatible, functionally equivalent linear regulator that is suitable for ceramic output capacitors, refer to the MAX8875 data sheet. Bypass the MAX8885's input with a 1F or greater capacitor to GND. Place this capacitor close to the device (<5mm).
Operating Region and Power Dissipation
The MAX8885'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 MAX8885 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 MAX8885's GND pin 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.
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7
150mA, Low-Dropout Linear Regulator with Power-OK Output MAX8885
PSRR and Operation from Sources Other than Batteries
The MAX8885 is designed to allow 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 MAX8885's line- and load-transient responses. put capacitor is chosen to comply with the Region of Stable COUT ESR vs. Load Current graph.
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 MAX8885 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-to-source onresistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics). VDROPOUT = VIN - VOUT = RDS(ON) * IOUT
Load-Transient Considerations
The MAX8885's load-transient response graphs (see Typical Operating Characteristics) show three components of the output response. The first (and most significant) component is the abrupt drop in output voltage due to the capacitor's ESR. The magnitude of the voltage drop is directly proportional to the output capacitor's ESR and the size of the load transient and is independent of the regulator's transient response. The second component is the output voltage recovery, which is a function of the regulator's loop response and the capacitance at the output. The third component is a DC shift in the output voltage resulting from the regulator's finite output impedance. To improve the MAX8885's load-transient response, increase the output capacitor's value and decrease its ESR. Take care to ensure that the out-
Chip Information
TRANSISTOR COUNT: 266
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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