MAX1857 Datasheet, PDF (1/10 Pages) Maxim Integrated Products – 500mA, Low-Dropout, Ripple-Rejecting LDO in MAX

19-1812; Rev 0; 1/01
500mA, Low-Dropout,
Ripple-Rejecting LDO in µMAX
General Description
The MAX1857 low-dropout linear regulator operates
from a +2.5V to +5.5V supply and delivers a guaran-
teed 500mA load current with low 120mV dropout. The
high-accuracy (±1%) output voltage is preset at an
internally trimmed 4.75V or can be adjusted from 1.25V
to 5.0V with an external resistive divider.
An internal PMOS pass transistor allows the low 135µA
supply current to remain independent of load, making
this device ideal for portable battery-operated equip-
ment such as personal digital assistants (PDAs), cellu-
lar phones, cordless phones, base stations, and
notebook computers.
Other features include an active-low open-drain reset
output with a 4.5ms timeout period that indicates when
the output is out of regulation, a 0.1µA shutdown mode,
short-circuit protection, and thermal shutdown protec-
tion. The device is available in a miniature 8-pin µMAX
package. For higher power applications, refer to the
MAX1792 and MAX1793 data sheets.
Features
o Guaranteed 500mA Output Current
o Low 120mV Dropout at 500mA
o Up to ±1% Output Voltage Accuracy
Preset at 4.75V
Adjustable from 1.25V to 5.0V
o Reset Output with 4.5ms Timeout Period
o Low 135µA Ground Current
o 0.1µA Shutdown Current
o Thermal Overload Protection
o Output Current Limit
o Tiny µMAX Package
________________________Applications
Notebook Computers
Cellular and Cordless Telephones
PDAs
Palmtop Computers
Base Stations
USB Hubs
Docking Stations
Ordering Information
PART*
MAX1857EUA47
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
8 µMAX
*Contact factory for other preset output voltages.
Typical Operating Circuit
V_IN = +5V
NINC
OUT
C_IN
IN
OUT
1µF
MAX1857
ON
SHDN
RST
OFF
SET
GND
V_OUT = 4.75V
C_OUT
3.3µF
R_RST
100k
TO
µC
TOP VIEW
Pin Configuration
IN 1
IN 2
RST 3
SHDN 4
MAX1857
8 OUT
7 OUT
6 SET
5 GND
µMAX
________________________________________________________________ Maxim Integrated Products 1
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