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 pre-
set output voltages in the +1.5V to +3.3V range.
An internal PMOS pass transistor allows the low 55µA
supply current to remain independent of load, making
these devices ideal for portable battery-powered equip-
ment such as personal digital assistants (PDAs), cellu-
lar 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.
________________________Applications
Notebook Computers
Wireless Handsets
PDAs and Palmtop Computers
Digital Cameras
PCMCIA Cards
Hand-Held Instruments
Features
♦Guaranteed 300mA Ouput Current (500mA for
pulsed loads)
♦Low 100mV Dropout at 200mA Load
♦POK Output (MAX8888)
♦42µVRMS Ouput Noise (MAX8887)
♦Preset Output Voltages (1.5V, 1.8V, 2.85V, and
3.3V)
♦55µA No-Load Supply Current
♦Thermal-Overload and Short–Circuit Protection
♦Foldback Ouput Current-Limit Protection
♦60dB PSRR at 1kHz
♦0.1µA Shutdown Current
♦Thin 5-Pin SOT23 Package, 1mm High
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
________________________________________________________________ Maxim Integrated Products 1
GND
BPSHDN
15OUTIN
MAX8887
TOP VIEW
2
34
GND
POKSHDN
15OUTIN
MAX8888
2
34
Pin Configurations
MAX8887
MAX8888
ON
OFF
INPUT
+2.5V TO +5.5V
IN
SHDN
GND
(BP)
POK
OUT
VOUT
300mA
CIN
2.2µF
COUT
2.2µF
CBP
0.01µF
( ) ARE FOR MAX8887 ONLY.
Typical Operating Circuit
19-1859; Rev 0; 12/00
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
PART TEMP
RANGE
PIN-
PACKAGE
TOP
MARK
M A X8 8 8 7 E Z K15 -40°C to +85°C 5-SOT23 ADQD
MAX8887EZK18 -40°C to +85°C 5-SOT23 ADPX
MAX8887EZK29 -40°C to +85°C 5-SOT23 ADPY
MAX8887EZK33 -40°C to +85°C 5-SOT23 ADPZ
MAX8887EZKxy* -40°C to +85°C 5-SOT23 –
M A X8 8 8 8 E Z K15 -40°C to +85°C 5-SOT23 ADQE
MAX8888EZK18 -40°C to +85°C 5-SOT23 ADQA
MAX8888EZK29 -40°C to +85°C 5-SOT23 ADQB
MAX8888EZK33 -40°C to +85°C 5-SOT23 ADQC
MAX8888EZKxy* -40°C to +85°C 5-SOT23 –
*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.
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN = VOUT + 1V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 1)
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.
IN, SHDN, POK, to GND........................................-0.3V to +6.0V
OUT, BP to GND ............................................-0.3 to (VIN + 0.3V)
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (TA= +70°C)
5-Pin SOT23 (derate 9.1mW/°C above +70°C)............727mW
Operating Temperature Ranges..........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+500°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Voltage VIN 2.5 5.5 V
Input Undervoltage Lockout VIN rising
(2% typical hysteresis) 2.15 2.4 V
TA = +25°C, IOUT = 100mA -1.2 +1.2
IOUT = 100µA to 300mA,
TA = 0°C to +85°C-2 +2
Output Voltage Accuracy
IOUT = 100µA to 300mA -3 +3
%
Continuous 300
Maximum Output Current 10ms pulse 500 mA
VOUT = 0 300
Current Limit VOUT > 93% of nominal value 420 mA
No load 55 100
Ground-Pin Current IOUT = 300mA 65 µA
IOUT = 1mA 0.5
IOUT = 200mA 100 200
Dropout Voltage (Note 2) VOUT = +3.3V
IOUT = 300mA 150
mV
Line Regulation VIN =2.5V or (VOUT + 0.4V) to 5.5V,
IOUT = 5mA -0.15 0 0.15 %/V
MAX8887 10Hz to 100kHz, CBP = 0.01µF,
COUT = 2.2µF, ESRCOUT < 0.1Ω42
Output Noise
MAX8888 10Hz to 100kHz, COUT = 2.2µF,
ESRCOUT < 0.1Ω360
µVRMS
MAX8887 f < 1kHz, CBP = 0.01µF,
COUT = 4.7µF, ESRCOUT < 0.1Ω60
PSRR
MAX8888 f < 1kHz, COUT = 2.2µF,
ESRCOUT < 0.1Ω40
dB
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
_______________________________________________________________________________________ 3
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SHUTDOWN
Shutdown Supply Current SHDN = GND, VIN = 5.5V 0.1 2 µA
VIH 2.5V ≤ VIN ≤ 5.5V 1.6
SHDN Input Threshold VIL 2.5V ≤ VIN ≤ 5.5V 0.6 V
SHDN Input Bias Current SHDN = IN or GND 10 100 nA
OUT Discharge Resistance in
Shutdown SHDN = GND 650 1100 Ω
POK (MAX8888 ONLY)
POK Trip Level, Referred to OUT
Set Point
VOUT falling
(1% typical hysteresis) 90 92.5 95 %
Operating IN Voltage Range for
Valid POK 1.0 5.5 V
POK Output Voltage Low VOL ISINK = 1mA 0.1 V
POK Output Leakage Current VPOK = 5.5V, SHDN = IN 100 nA
THERMAL PROTECTION
Thermal Shutdown Temperature 170 °C
Thermal Shutdown Hysteresis 20 °C
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT + 1V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 1)
Note 1: All parts are 100% tested at TA= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: Typical and maximum dropout voltage for different output voltages are shown in Typical Operating Characteristics curve.
Typical Operating Characteristics
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
0
1.0
0.5
2.0
1.5
3.0
2.5
3.5
2.0 3.0 3.52.5 4.0 4.5 5.0 5.5
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX8887-8 toc01
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
IOUT = 0
IOUT = 300mA
-1.0
-0.6
-0.8
0.0
-0.2
-0.4
0.2
0.4
0.8
0.6
1.0
10050 150 200 250 300
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
MAX8887-8 toc02
LOAD CURRENT (mA)
% DEVIATION (%)
0
-0.05
-0.02
-0.03
-0.04
-0.01
0.0
0.01
0.02
0.03
0.04
0.05
-40 10-15 356085
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
MAX8887-8 toc03
TEMPERATURE (°C)
% DEVIATION
I
OUT
= 0
V
IN
= V
OUT
+ 500mV
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
4 _______________________________________________________________________________________
0
20
40
60
80
100
120
140
160
0 10050 150 200 250 300
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8887-8 toc04
LOAD CURRENT (mA)
VDROPOUT (mV)
TA = +25°C
TA = +85°C
TA = -40°C
0
50
100
150
200
250
300
2.5 2.7 2.9 3.1 3.3
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
MAX8887-8 toc05
VOUT (V)
VDROPOUT (mV)
IOUT = 200mA
MAXIMUM
TYPICAL
0 1.0 2.0 3.0 4.0 5.0
INPUT VOLTAGE (V)
0
50
25
100
75
125
150
GROUND-PIN CURRENT vs. INPUT VOLTAGE
MAX8887-8 toc06
GROUND-PIN CURRENT (µA)
ILOAD = 300mA
ILOAD = 0
0
20
60
40
80
100
010050 150 200 250 300
GROUND-PIN CURRENT vs. LOAD CURRENT
MAX8887-8 toc07
LOAD CURRENT (mA)
GROUND-PIN CURRENT (µA)
VIN = +5.5V
VIN = +3.8V
50
56
54
52
58
60
62
64
66
68
70
-40 10-15 35 60 85
GROUND-PIN CURRENT vs. TEMPERATURE
MAX8887-8 toc08
TEMPERATURE (°C)
GROUND-PIN CURRENT (µA)
I
OUT
= 0
V
IN
= V
OUT
+ 500mV
70
0.01 0.1 1 10 100 1000
60
50
40
30
20
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX8887-8 toc09
FREQUENCY (kHz)
PSRR (dB)
10
0
COUT = 2.2µF
CBP = 0.01µF
VOUT = +3.30V
ILOAD = 30mA MAX8887 ONLY
MAX8887
OUTPUT NOISE DC TO 1MHz
VOUT
50µV/div
MAX8887-9 toc10
TIME (40ms/div)
VOUT = +1.8V, VIN = 3.8V, ILOAD = 15mA
LOAD-TRANSIENT RESPONSE
50mV/div
AC-COUPLED
MAX8887-9 toc11
300mA
10mA
VOUT
IOUT
VOUT = +3.3V
VIN = +3.8V
TIME (10µs/div)
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
_______________________________________________________________________________________ 5
LINE-TRANSIENT RESPONSE
MAX8887-9 toc13
20mV/div
AC-COUPLED
+4V
+4.5V
VOUT
VIN
VOUT = +3.3V
ILOAD = 100mA
TIME (100µs/div)
SHUTDOWN WAVEFORM
MAX8887-9 toc14
VSHDN
1V/div
DC-COUPLED
2V/div
VOUT
VOUT = +3.3V, RLOAD = 10Ω
TIME (20µs/div)
POK WAVEFORM
MAX8887-9 toc15
2V/div
2V/div
2V/div
VOUT
VPOK
VIN
VOUT = +3.3V, RLOAD = 100Ω
TIME (20ms/div)
Pin Description
MAX8887 MAX8888 NAME FUNCTION
11IN
Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with 2.2µF
capacitor to GND (see Capacitor Selection and Regulator Stability).
2 2 GND Ground
33SHDN Active-Low Shutdown Input. A logic low reduces the supply current to below 0.1µA.
In shutdown, POK and OUT are driven low. Connect to IN for normal operation.
—4POK
Open-Drain Active-Low POK Output. POK remains low while the output voltage (VOUT) is
below the reset threshold. Connect a 100kΩ pullup resistor to OUT to obtain a logic level
output. POK is driven low in shutdown. If not used, leave this pin unconnected.
4—BP Reference Bypass. Bypass with a low-leakage 0.01µF ceramic capacitor.
5 5 OUT Regulator Output. Sources up to 300mA guaranteed. Bypass with 2.2µF (<0.2Ω typical
ESR) ceramic capacitor to GND.
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
MAX8887-9 toc12
50mV/div
AC-COUPLED
300mA
10mA
VOUT
IOUT
VOUT = +3.3V
VIN = +3.4V
TIME (10µs/div)
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
Detailed Description
The MAX8887/MAX8888 are low-dropout, low-quies-
cent-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 +1.5 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 tran-
sistor, and internal feedback voltage divider.
Internal P-Channel Pass Transistor
The MAX8887/MAX8888 feature a 0.5ΩP-channel
MOSFET pass transistor. Unlike similar designs using
PNP pass transistors, P-channel MOSFETs require no
base drive, which reduces quiescent current. PNP-
based 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 55µA of quiescent current under
heavy loads as well as in dropout.
Ouput Voltage Selection
The MAX8887/MAX8888 are supplied with various fac-
tory-set output voltages ranging from 1.5V to 3.3V. The
part number’s two-digit suffix identifies the nominal out-
put voltage. For example, the MAX8887EUK33 has a
preset output voltage of 3.3V (see Ordering Infor-
mation).
Shutdown
Drive SHDN low to enter shutdown. During shutdown,
the output is disconnected from the input and supply
current drops to 0.1µA. When in shutdown, POK and
OUT are driven low. SHDN can be pulled as high as
6V, regardless of the input and output voltages.
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 100kΩresistor works well for most
applications. POK can be used as a power-on-reset
(POR) signal to a microcontroller (µC) 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.
Current Limit
The MAX8887/MAX8888 monitor and control the pass
transistor’s gate voltage, limiting the output current to
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 dissipa-
tion in the MAX8887/MAX8888. When the junction tem-
perature exceeds TJ =+170°C, 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 20°C, resulting in a
pulsed output during continuous thermal overload con-
ditions. Thermal overload protection protects the
MAX8887/MAX8888 in the event of fault conditions. For
continuous operation, do not exceed the absolute maxi-
mum junction-temperature rating of TJ=+150°C.
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 ✕(VIN-
VOUT). The maximum allowed power dissipation is
727mW or:
PMAX = (TJ(MAX) - TA) / (θJC + θCA)
where TJ(MAX)-TAis the temperature difference
between the MAX8887/MAX8888 die junction and the
surrounding air; θJC is the thermal resistance from the
junction to the case; and θCA 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 oper-
ating region.
Noise Reduction
For the MAX8887 only, an external 0.01µF bypass
capacitor at BP creates a lowpass filter for noise reduc-
tion. The MAX8887 exhibits 42µVRMS of output voltage
noise with CBP = 0.01µF and COUT = 2.2µF (see
Typical Operating Characteristics).
Applications Information
Capacitor Selection and Regulator
Stability
Connect a 2.2µF ceramic capacitor between IN and
ground and a 2.2µF ceramic capacitor between OUT
and ground. The input capacitor (CIN) 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 out-
put capacitor such as 4.7µF.
The output capacitor’s (COUT) equivalent series resis-
tance (ESR) affects stability and output noise. Use out-
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
6 _______________________________________________________________________________________
put capacitors with an ESR of 0.1Ωor less to ensure sta-
bility and optimum transient response. Surface-mount
ceramic capacitors have very low ESR and are com-
monly available in values up to 10µF. Connect CIN and
COUT as close to the MAX8887/MAX8888 as possible to
minimize the impact of PC board trace inductance.
Noise, PSRR, and Transient Response
The MAX8887/MAX8888 are designed to operate with
low dropout voltages and low quiescent currents in bat-
tery-powered systems while still maintaining excellent
noise, transient response, and AC rejection. See the
Typical Operating Characteristics for a plot of power-
supply 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.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest usable sup-
ply 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 volt-
age 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
Chip Information
TRANSISTOR COUNT: 620
PROCESS: BiCMOS
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
_______________________________________________________________________________________ 7
SHUTDOWN
LOGIC
ERROR
AMP
1.25V
REF
95%
REF
P
OUT
POK
GND
IN
SHDN
MAX8888
THERMAL
SENSOR
MOS DRIVER
WITH ILIMIT
POK
Figure 1. Functional Diagram
0
100
200
300
400
0 1.0 2.0 3.00.5 1.5 2.5 3.5 4.0
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
(VIN - VOUT) (V)
MAXIMUM OUTPUT CURRENT (mA)
VOUT = +3.3V
VOUT = +2.85V
VOUT = +1.8V
MAXIMUM RECOMMENDED OUTPUT CURRENT
TA = +85°C
TA = +70°C
Figure 2. Power Operating Regions: Maximum Output Current
vs. Input Voltage
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
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
© 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information
THIN SOT23.EPS
