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19-1859; Rev 1; 12/01
Low-Dropout, 300mA Linear Regulators in SOT23
General Description
The MAX8887/MAX8888 low-dropout linear regulators operate from a 2.5V to 5.5V input and deliver up to 300mA continuous (500mA pulsed) current. The MAX8887 is optimized for low-noise operation, while the MAX8888 includes an open-drain POK ouput flag. Both regulators feature exceptionally low 100mV dropout at 200mA. These devices are available in a variety of preset output voltages in the 1.5V to 3.3V range. An internal PMOS pass transistor allows the low 55A supply current to remain independent of load, making these devices ideal for portable battery-powered equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, and notebook computers. Other features include a micropower shutdown mode, short-circuit protection, thermal shutdown protection, and an active-low open-drain power-OK (POK) output that indicates when the output is out of regulation. The MAX8887/MAX8888 are available in a thin 5-pin SOT23 package that is only 1mm high.
Features
o Guaranteed 300mA Output Current (500mA for Pulsed Loads) o Low 100mV Dropout at 200mA Load o POK Output (MAX8888) o 42VRMS Output Noise (MAX8887) o Preset Output Voltages (1.5V, 1.8V, 2.85V, and 3.3V) o 55A No-Load Supply Current o Thermal Overload and Short-Circuit Protection o Foldback Output Current-Limit Protection o 60dB PSRR at 1kHz o 0.1A Shutdown Current o Thin 5-Pin SOT23 Package, 1mm High
MAX8887/MAX8888
Ordering Information
PART TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PINPACKAGE 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 5 SOT23-5 TOP MARK ADQD ADPX ADPY ADPZ -- ADQE ADQA ADQB ADQC --
________________________Applications
Notebook Computers Wireless Handsets PDAs and Palmtop Computers Digital Cameras PCMCIA Cards Hand-Held Instruments
MAX8887EZK15-T MAX8887EZK18-T MAX8887EZK29-T MAX8887EZK33-T MAX8888EZK15-T MAX8888EZK18-T MAX8888EZK29-T MAX8888EZK33-T
MAX8887EZKxy-T* -40C to +85C
MAX8888EZKxy-T* -40C to +85C
Typical Operating Circuit
INPUT 2.5V TO 5.5V IN CIN 2.2F OUT VOUT 300mA COUT 2.2F POK ON SHDN OFF GND (BP) CBP 0.01F
*Other versions (xy) between +1.5 and +3.3V are available in 100mV increments. Contact factory for other versions. Minimum order quantity is 25,000 units.
Pin Configurations
TOP VIEW
IN 1 5 OUT IN 1 5 OUT
MAX8887 MAX8888
GND 2
MAX8887
GND 2
MAX8888
SHDN 3 ( ) ARE FOR MAX8887 ONLY.
4
BP
SHDN 3
4
POK
________________________________________________________________ Maxim Integrated Products
1
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Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, POK, to GND...........................................-0.3V to +6V OUT, BP to GND ............................................-0.3 to (VIN + 0.3V) Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70C) 5-Pin SOT23 (derate 9.1mW/C above +70C)............727mW Operating Temperature Ranges..........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+500C
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 + 1V, SHDN = IN, TA = -40C to +85C, unless otherwise noted.) (Note 1)
PARAMETER Input Voltage Input Undervoltage Lockout SYMBOL VIN VIN rising (2% typical hysteresis) TA = +25C, IOUT = 100mA Output Voltage Accuracy IOUT = 100A to 300mA, TA = 0C to +85C IOUT = 100A to 300mA Maximum Output Current Current Limit Ground-Pin Current Continuous 10ms pulse VOUT = 0 VOUT > 93% of nominal value No load IOUT = 300mA IOUT = 1mA Dropout Voltage (Note 2) VOUT = +3.3V IOUT = 200mA IOUT = 300mA Line Regulation VIN = 2.5V or (VOUT + 0.4V) to 5.5V, IOUT = 5mA MAX8887 Output Noise MAX8888 MAX8887 PSRR MAX8888 10Hz to 100kHz, CBP = 0.01F, COUT = 2.2F, ESRCOUT < 0.1 10Hz to 100kHz, COUT = 2.2F, ESRCOUT < 0.1 f < 1kHz, CBP = 0.01F, COUT = 4.7F, ESRCOUT < 0.1 f < 1kHz, COUT = 2.2F, ESRCOUT < 0.1 -0.15 300 420 55 65 0.5 100 150 0 42 VRMS 360 60 dB 40 0.15 %/V 200 100 CONDITIONS MIN 2.5 2.15 -1.2 -2 -3 300 500 TYP MAX 5.5 2.4 +1.2 +2 +3 mA mA A % UNITS V V
mV
2
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Low-Dropout, 300mA Linear Regulators in SOT23
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT + 1V, SHDN = IN, TA = -40C to +85C, unless otherwise noted.) (Note 1)
PARAMETER SHUTDOWN Shutdown Supply Current SHDN Input Threshold SHDN Input Bias Current OUT Discharge Resistance in Shutdown POK (MAX8888 ONLY) POK Trip Level, Referred to OUT Set Point Operating IN Voltage Range for Valid POK POK Output Voltage Low POK Output Leakage Current THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis 170 20 C C VOL ISINK = 1mA VPOK = 5.5V, SHDN = IN VOUT falling (1% typical hysteresis) 90 1.0 92.5 95 5.5 0.1 100 % V V nA VIH VIL SHDN = GND, VIN = 5.5V 2.5V VIN 5.5V 2.5V VIN 5.5V SHDN = IN or GND SHDN = GND 10 650 1.6 0.6 100 1100 0.1 2 A V nA SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX8887/MAX8888
Note 1: All parts are 100% tested at TA = +25C. Limits over the operating temperature range are guaranteed by design. Note 2: Typical and maximum dropout voltage for different output voltages are shown in the Typical Operating Characteristics curve.
Typical Operating Characteristics
(Typical Operating Circuit, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8887/8 toc01
OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT
MAX8887/8 toc02
OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE
0.04 0.03 0.02 % DEVIATION 0.01 0.0 -0.01 -0.02 -0.03 -0.04 -0.05 IOUT = 0 VIN = VOUT + 500mV
MAX8887/8 toc03
3.5 3.0 OUTPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 IOUT = 0 IOUT = 300mA
1.0 0.8 0.6 % DEVIATION (%) 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0
0.05
5.5
0
50
100
150
200
250
300
-40
-15
10
35
60
85
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
TEMPERATURE (C)
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Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25C, unless otherwise noted.)
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8887/8 toc04
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
MAX8887/8 toc05
GROUND-PIN CURRENT vs. INPUT VOLTAGE
MAX8887/8 toc06
160 140 120
VDROPOUT (mV)
300 IOUT = 200mA 250 MAXIMUM VDROPOUT (mV) 200 150 TYPICAL 100
150 125 100 ILOAD = 300mA 75 50 25 0 ILOAD = 0
TA = +85C
100 80 60 40 20 0 0 50 100 150 200 250 300 LOAD CURRENT (mA) TA = -40C
50 0 2.5 2.7 2.9 VOUT (V) 3.1 3.3
GROUND-PIN CURRENT (A)
TA = +25C
0
1.0
2.0
3.0
4.0
5.0
INPUT VOLTAGE (V)
GROUND-PIN CURRENT vs. LOAD CURRENT
MAX8887/8 toc07
GROUND-PIN CURRENT vs. TEMPERATURE
MAX8887/8 toc08
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX8887/8 toc09
100 VIN = 5.5V
GROUND-PIN CURRENT (A)
70 68 GROUND-PIN CURRENT (A) 66 64 IOUT = 0 VIN = VOUT + 500mV
70 60 50 PSRR (dB) 40 30 20 10 0 VOUT = 3.30V ILOAD = 30mA 0.01 0.1 1 10 COUT = 2.2F CBP = 0.01F
80 VIN = 3.8V
60
62 60 58 56 54 52
40
20
0 0 50 100 150 200 250 300 LOAD CURRENT (mA)
50 -40 -15 10 35 60 85 TEMPERATURE (C)
MAX8887 ONLY 100 1000
FREQUENCY (kHz)
MAX8887 OUTPUT NOISE DC TO 1MHz
MAX8887/8 toc10
LOAD-TRANSIENT RESPONSE
MAX8887/8 toc11
300mA IOUT VOUT 50V/div VOUT 50mV/div AC-COUPLED
10mA
VOUT = 1.8V, VIN = 3.8V, ILOAD = 15mA 40ms/div 10s/div
VOUT = 3.3V VIN = 3.8V
4
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Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE NEAR DROPOUT
MAX8887/8 toc12
LINE-TRANSIENT RESPONSE
MAX8887/8 toc13
300mA 4.5V IOUT 10mA VIN VOUT 50mV/div AC-COUPLED VOUT 20mV/div AC-COUPLED VOUT = 3.3V ILOAD = 100mA 100s/div 4V
VOUT = 3.3V VIN = 3.4V 10s/div
SHUTDOWN WAVEFORM
MAX8887/8 toc14
POK WAVEFORM
MAX8887/8 toc15
VSHDN 2V/div
VIN
VOUT = 3.3V, RLOAD = 100 2V/div
VOUT 1V/div DC-COUPLED
VOUT
2V/div
VPOK
2V/div
VOUT = 3.3V, RLOAD = 10 20s/div 20ms/div
Pin Description
MAX8887 1 2 3 MAX8888 1 2 3 NAME IN GND SHDN FUNCTION Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with 2.2F capacitor to GND (see the Capacitor Selection and Regulator Stability section). Ground Active-Low Shutdown Input. A logic low reduces the supply current to below 0.1A. In shutdown, POK and OUT are driven low. Connect to IN for normal operation. Open-Drain Active-Low POK Output. POK remains low while the output voltage (VOUT) is below the reset threshold. Connect a 100k pullup resistor to OUT to obtain a logic level output. POK is driven low in shutdown. If not used, leave this pin unconnected. Reference Bypass. Bypass with a low-leakage 0.01F ceramic capacitor. Regulator Output. Sources up to 300mA guaranteed. Bypass with 2.2F (<0.2 typical ESR) ceramic capacitor to GND.
-- 4 5
4 -- 5
POK BP OUT
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Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
Detailed Description
The MAX8887/MAX8888 are low-dropout, low-quiescent-current linear regulators designed primarily for battery-powered applications. The devices supply loads up to 300mA and are available in several fixed output voltages in the 1.5V to 3.3V range. The MAX8887 is optimized for low-noise operation, while the MAX8888 includes an open-drain POK output flag. As illustrated in Figure 1, the MAX8888 consists of a 1.25V reference, error amplifier, P-channel pass transistor, and internal feedback voltage divider. 0.8A (typ). This current limit is reduced to 500mA (typ) when the output voltage is below 93% of the nominal value to provide foldback current limiting.
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the MAX8887/MAX8888. When the junction temperature exceeds TJ =+170C, a thermal sensor turns off the pass transistor, allowing the device to cool. The thermal sensor turns the pass transistor on again after the junction temperature cools by 20C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection protects the MAX8887/MAX8888 in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ=+150C.
Internal P-Channel Pass Transistor
The MAX8887/MAX8888 feature a 0.5 P-channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P-channel MOSFETs require no base drive, which reduces quiescent current. PNPbased regulators also waste considerable current in dropout when the pass transistor saturates and use high base drive currents under large loads. The MAX8887/MAX8888 do not suffer from these problems and consume only 55A of quiescent current under heavy loads as well as in dropout.
Operating Region and Power Dissipation
The MAX8887/MAX8888's maximum power dissipation depends on the thermal resistance of the IC package and circuit board. The temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipated in the device is P = IOUT (VINV OUT ). The maximum allowed power dissipation is 727mW or: PMAX = (TJ(MAX) - TA) / (JC + CA) where T J(MAX) -T A is the temperature difference between the MAX8887/MAX8888 die junction and the surrounding air; JC is the thermal resistance from the junction to the case; and CA is the thermal resistance from the case through PC board, copper traces, and other materials to the surrounding air. Refer to Figure 2 for the MAX8887/MAX888 valid operating region.
Output Voltage Selection
The MAX8887/MAX8888 are supplied with various factory-set output voltages ranging from 1.5V to 3.3V. The part number's two-digit suffix identifies the nominal output voltage. For example, the MAX8887EZK33 has a preset output voltage of 3.3V (see the Ordering Information).
Shutdown
Drive SHDN low to enter shutdown. During shutdown, the output is disconnected from the input and supply current drops to 0.1A. When in shutdown, POK and OUT are driven low. SHDN can be pulled as high as 6V, regardless of the input and output voltages.
Noise Reduction
For the MAX8887 only, an external 0.01F bypass capacitor at BP creates a lowpass filter for noise reduction. The MAX8887 exhibits 42VRMS of output voltage noise with CBP = 0.01F and COUT = 2.2F (see the Typical Operating Characteristics).
Power-OK Output
The power-OK output (POK) pulls low when OUT is less than 93% of the nominal regulation voltage. Once OUT exceeds 93% of the nominal voltage, POK goes high impedance. POK is an open-drain N-channel output. To obtain a logic level output, connect a pullup resistor from POK to OUT. A 100k resistor works well for most applications. POK can be used as a power-on-reset (POR) signal to a microcontroller (C) or to drive other logic. Adding a capacitor from POK to ground creates POK delay. When the MAX8887 is shut down, POK is held low independent of the output voltage. If unused, leave POK grounded or unconnected.
Applications Information
Capacitor Selection and Regulator Stability
Connect a 2.2F ceramic capacitor between IN and ground and a 2.2F ceramic capacitor between OUT and ground. The input capacitor (C IN ) lowers the source impedance of the input supply. Reduce noise and improve load-transient response, stability, and power-supply rejection by using a larger ceramic output capacitor such as 4.7F. The output capacitor's (COUT) equivalent series resistance (ESR) affects stability and output noise. Use out-
Current Limit
The MAX8887/MAX8888 monitor and control the pass transistor's gate voltage, limiting the output current to
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Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
IN SHDN
ERROR AMP SHUTDOWN LOGIC
MOS DRIVER WITH ILIMIT
P
OUT
MAX8888
POK THERMAL SENSOR 1.25V REF 95% REF POK
GND
Figure 1. Functional Diagram
Noise, PSRR, and Transient Response
The MAX8887/MAX8888 are designed to operate with low dropout voltages and low quiescent currents in battery-powered systems while still maintaining excellent noise, transient response, and AC rejection. See the Typical Operating Characteristics for a plot of powersupply rejection ratio (PSRR) versus frequency. When operating from noisy sources, 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.
MAXIMUM OUTPUT CURRENT (mA)
put capacitors with an ESR of 0.1 or less to ensure stability and optimum transient response. Surface-mount ceramic capacitors have very low ESR and are commonly available in values up to 10F. Connect CIN and COUT as close to the MAX8887/MAX8888 as possible to minimize the impact of PC board trace inductance.
MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE (POWER DISSIPATION LIMIT)
400 TA = +85C TA = +70C
MAXIMUM RECOMMENDED OUTPUT CURRENT
300
200
VOUT = +2.85V
100
0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 (VIN - VOUT) (V)
Input-Output (Dropout) Voltage
A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage at which the output is regulated. In battery-powered systems, this determines the useful end-of-life battery voltage. The MAX8887/MAX8888 use a P-channel MOSFET pass transistor. Its dropout voltage is a function of drain-to-source on-resistance (R DS(ON) ) multiplied by the load current (see the Typical Operating Characteristics). VDROPOUT = VIN - VOUT = RDS(ON) IOUT
Figure 2. Power Operating Regions: Maximum Output Current vs. Input Voltage
TRANSISTOR COUNT: 620 PROCESS: BiCMOS
7
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VOUT = +3.3V
Chip Information
VOUT = +1.8V
Low-Dropout, 300mA Linear Regulators in SOT23 MAX8887/MAX8888
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
THIN SOT23.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) 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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