MAX8887/MAX8888 Low-Dropout, 300mA
19-1859; Rev 4; 7/09
Low-Dropout, 300mA Linear Regulators in SOT23
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 power-OK (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 55µA
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 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
Features
♦ Guaranteed 300mA Output Current (500mA for
Pulsed Loads)
♦ Low 100mV Dropout at 200mA Load
♦ POK Output (MAX8888)
♦ 42µVRMS Output 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 Output Current-Limit Protection
♦ 60dB PSRR at 1kHz
♦ 0.1µA Shutdown Current
♦ Thin 5-Pin SOT23 Package, 1mm High
Ordering Information
TEMP
RANGE
PART
PINPACKAGE
TOP
MARK
MAX8887EZK15+T
-40°C to +85°C 5 SOT23
ADQD
MAX8887EZK18+T
-40°C to +85°C 5 SOT23
ADPX
MAX8887EZK29+T
-40°C to +85°C 5 SOT23
ADPY
MAX8887EZK33+T
-40°C to +85°C 5 SOT23
ADPZ
MAX8887EZKxy+T*
-40°C to +85°C 5 SOT23
—
MAX8888EZK15+T
-40°C to +85°C 5 SOT23
ADQE
PDAs and Palmtop Computers
MAX8888EZK18+T
-40°C to +85°C 5 SOT23
ADQA
Digital Cameras
MAX8888EZK18/V+T
-40°C to +85°C 5 SOT23
—
PCMCIA Cards
MAX8888EZK29+T
-40°C to +85°C 5 SOT23
ADQB
Hand-Held Instruments
MAX8888EZK33+T
-40°C to +85°C 5 SOT23
ADQC
MAX8888EZKxy+T*
-40°C to +85°C 5 SOT23
—
Typical Operating Circuit
*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.
+Denotes a lead(Pb)-free RoHS-compliant package.
/V denotes an automotive qualified part.
Pin Configurations
VOUT
300mA
INPUT
2.5V TO 5.5V
IN
CIN
2.2µF
OUT
COUT
2.2µF
MAX8887
MAX8888
TOP VIEW
IN
1
5
OUT
IN
1
5
OUT
4
POK
POK
ON
SHDN
GND 2
(BP)
OFF
GND
MAX8887
GND 2
MAX8888
CBP
0.01µF
SHDN 3
4
BP
SHDN 3
( ) ARE FOR MAX8887 ONLY.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX8887/MAX8888
General Description
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, POK, to GND...........................................-0.3V to +7V
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 Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+500°C
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 = -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
Input Voltage
Input Undervoltage Lockout
Output Voltage Accuracy
SYMBOL
CONDITIONS
VIN
Current Limit
Ground-Pin Current
MAX
UNITS
2.5
5.5
V
2.15
2.4
V
TA = +25°C, IOUT = 100mA
-1.2
+1.2
-2
+2
-3
+3
IOUT = 100µA to 300mA,
TA = 0°C to +85°C
Continuous
300
10ms pulse
VOUT = 0
300
VOUT > 93% of nominal value
420
mA
No load
55
IOUT = 300mA
IOUT = 1mA
65
0.5
IOUT = 200mA
100
IOUT = 300mA
150
VOUT = +3.3V
Line Regulation
VIN = 2.5V or (VOUT + 0.4V) to 5.5V,
IOUT = 5mA
-0.15
0
MAX8887
10Hz to 100kHz, CBP = 0.01µF,
COUT = 2.2µF, ESRCOUT < 0.1Ω
42
MAX8888
10Hz to 100kHz, COUT = 2.2µF,
ESRCOUT < 0.1Ω
360
MAX8887
f < 1kHz, CBP = 0.01µF,
COUT = 4.7µF, ESRCOUT < 0.1Ω
60
MAX8888
f < 1kHz, COUT = 2.2µF,
ESRCOUT < 0.1Ω
40
Output Noise
PSRR
%
mA
500
Dropout Voltage (Note 2)
2
TYP
VIN rising
(2% typical hysteresis)
IOUT = 100µA to 300mA
Maximum Output Current
MIN
100
µA
200
mV
0.15
%/V
µVRMS
dB
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
(VIN = VOUT + 1V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.1
2
µA
SHUTDOWN
SHDN = GND, VIN = 5.5V
Shutdown Supply Current
SHDN Input Threshold
VIH
2.5V ≤ VIN ≤ 5.5V
VIL
2.5V ≤ VIN ≤ 5.5V
1.6
V
0.6
SHDN Input Bias Current
SHDN = IN or GND
10
100
nA
OUT Discharge Resistance in
Shutdown
SHDN = GND
650
1100
Ω
92.5
95
%
5.5
V
ISINK = 1mA
0.1
V
VPOK = 5.5V, SHDN = IN
100
nA
POK (MAX8888 ONLY)
POK Trip Level, Referred to OUT
Set Point
VOUT falling
(1% typical hysteresis)
90
Operating IN Voltage Range for
Valid POK
1.0
POK Output Voltage Low
VOL
POK Output Leakage Current
THERMAL PROTECTION
Thermal Shutdown Temperature
170
°C
Thermal Shutdown Hysteresis
20
°C
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 the Typical Operating Characteristics
curves.
Typical Operating Characteristics
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE ACCURACY
vs. LOAD CURRENT
0.8
0.6
2.0
1.5
1.0
0.5
0
2.5
3.0
3.5
4.0
4.5
INPUT VOLTAGE (V)
5.0
5.5
0.03
0.02
0.4
0.2
0.0
-0.2
0.01
0.0
-0.01
-0.4
-0.02
-0.6
-0.03
-0.8
-0.04
-1.0
2.0
IOUT = 0
VIN = VOUT + 500mV
0.04
% DEVIATION
% DEVIATION (%)
OUTPUT VOLTAGE (V)
IOUT = 300mA
2.5
0.05
MAX8887/8 toc02
IOUT = 0
3.0
1.0
MAX8887/8 toc01
3.5
OUTPUT VOLTAGE ACCURACY
vs. TEMPERATURE
MAX8887/8 toc03
OUTPUT VOLTAGE vs. INPUT VOLTAGE
-0.05
0
50
100
150
200
LOAD CURRENT (mA)
250
300
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
3
MAX8887/MAX8888
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
MAXIMUM
VDROPOUT (mV)
TA = +85°C
100
80
60
200
150
TYPICAL
100
TA = -40°C
40
50
20
0
50
100
150
200
250
100
ILOAD = 300mA
75
50
ILOAD = 0
0
2.5
300
125
25
0
0
MAX8887/8 toc06
IOUT = 200mA
250
GROUND-PIN CURRENT vs. INPUT VOLTAGE
150
GROUND-PIN CURRENT (µA)
TA = +25°C
120
2.7
2.9
3.1
3.3
0
1.0
2.0
3.0
5.0
VOUT (V)
INPUT VOLTAGE (V)
GROUND-PIN CURRENT vs. LOAD CURRENT
GROUND-PIN CURRENT vs. TEMPERATURE
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
VIN = 3.8V
60
40
70
66
60
64
50
62
60
58
56
20
MAX8887/8 toc09
80
IOUT = 0
VIN = VOUT + 500mV
68
PSRR (dB)
VIN = 5.5V
70
GROUND-PIN CURRENT (µA)
MAX8887/8 toc07
100
COUT = 2.2µF
CBP = 0.01µF
40
30
20
54
10
52
0
50
0
50
100
150
200
250
300
-40
LOAD CURRENT (mA)
-15
10
35
60
0
85
VOUT = 3.30V
ILOAD = 30mA
0.01
MAX8887 ONLY
0.1
TEMPERATURE (°C)
MAX8887
OUTPUT NOISE DC TO 1MHz
1
10
FREQUENCY (kHz)
LOAD-TRANSIENT RESPONSE
MAX8887/8 toc10
MAX8887/8 toc11
300mA
IOUT
10mA
VOUT
50mV/div
AC-COUPLED
VOUT
50µV/div
VOUT = 3.3V
VIN = 3.8V
VOUT = 1.8V, VIN = 3.8V, ILOAD = 15mA
40ms/div
4
4.0
LOAD CURRENT (mA)
MAX8887/8 toc08
VDROPOUT (mV)
MAX8887/8 toc04
140
300
MAX8887/8 toc05
DROPOUT VOLTAGE vs. OUTPUT VOLTAGE
DROPOUT VOLTAGE vs. LOAD CURRENT
160
GROUND-PIN CURRENT (µA)
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
10µs/div
_______________________________________________________________________________________
100
1000
Low-Dropout, 300mA Linear Regulators in SOT23
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
LINE-TRANSIENT RESPONSE
MAX8887/8 toc13
MAX8887/8 toc12
300mA
4.5V
IOUT
10mA
VIN
4V
VOUT
50mV/div
AC-COUPLED
VOUT
20mV/div
AC-COUPLED
VOUT = 3.3V
VIN = 3.4V
VOUT = 3.3V
ILOAD = 100mA
100µs/div
10µs/div
POK WAVEFORM
SHUTDOWN WAVEFORM
MAX8887/8 toc15
MAX8887/8 toc14
VSHDN
VIN
VOUT = 3.3V, RLOAD = 100Ω
2V/div
2V/div
VOUT
1V/div
DC-COUPLED
VOUT
2V/div
VPOK
2V/div
VOUT = 3.3V, RLOAD = 10Ω
20ms/div
20µs/div
Pin Description
MAX8887
MAX8888
NAME
1
1
IN
2
2
GND
3
3
SHDN
—
4
POK
4
—
BP
5
5
OUT
FUNCTION
Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with 2.2µF
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 0.1µA.
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 100kΩ 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 0.01µF ceramic capacitor.
Regulator Output. Sources up to 300mA guaranteed. Bypass with 2.2µF (<0.2Ω typical
ESR) ceramic capacitor to GND.
_______________________________________________________________________________________
5
MAX8887/MAX8888
Typical Operating Characteristics (continued)
(Typical Operating Circuit, TA = +25°C, unless otherwise noted.)
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
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.
Internal p-Channel Pass Transistor
The MAX8887/MAX8888 feature a 0.5Ω 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 uses
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.
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 0.1µA. 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 100kΩ resistor 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)
6
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 =+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 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=+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 ✕ (VINV OUT ). The maximum allowed power dissipation is
727mW or:
PMAX = (TJ(MAX) - TA) / (θJC + θCA)
where T J(MAX) -T A is 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 operating region.
Noise Reduction
For the MAX8887 only, an external 0.01µF bypass
capacitor at BP creates a lowpass filter for noise reduction. The MAX8887 exhibits 42µVRMS of output voltage
noise with CBP = 0.01µF and COUT = 2.2µF (see the
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 (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 4.7µF.
The output capacitor’s (COUT) equivalent series resistance (ESR) affects stability and output noise. Use output capacitors with an ESR of 0.1Ω or less to ensure
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
MAX8887/MAX8888
IN
SHDN
P
MOS DRIVER
WITH ILIMIT
ERROR
AMP
SHUTDOWN
LOGIC
OUT
MAX8888
POK
THERMAL
SENSOR
1.25V
REF
POK
95%
REF
GND
Figure 1. Functional Diagram
stability and optimum transient response. Surface-mount
ceramic capacitors have very low ESR and are commonly 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.
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
TA = +85°C
TA = +70°C
MAXIMUM RECOMMENDED OUTPUT CURRENT
300
2.0
2.5
VOUT = +1.8V
100
VOUT = +3.3V
200
VOUT = +2.85V
Input-Output (Dropout) Voltage
400
MAXIMUM OUTPUT CURRENT (mA)
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
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
0
0
0.5
1.0
1.5
3.0
3.5
4.0
(VIN - VOUT) (V)
Figure 2. Power Operating Regions: Maximum Output Current
vs. Input Voltage
_______________________________________________________________________________________
7
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
Package Information
Chip Information
TRANSISTOR COUNT: 620
PROCESS: BiCMOS
8
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in
the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
5 SOT23
Z5-1
21-0113
_______________________________________________________________________________________
Low-Dropout, 300mA Linear Regulators in SOT23
REVISION
NUMBER
REVISION
DATE
0
12/00
Initial release
1
12/01
Revised Output Voltage Selection section.
6
2
6/04
Revised Absolute Maximum Ratings.
2
3
11/06
Updated Ordering Information and package outlines.
4
7/09
Revised Ordering Information.
DESCRIPTION
PAGES
CHANGED
—
1, 8
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.
9 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products.
MAX8887/MAX8888
Revision History
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