LP3881 0.8A Fast-Response Ultra Low Dropout Linear Regulators
August 2003
LP3881
0.8A Fast-Response Ultra Low Dropout Linear
Regulators
General Description
The LP3881 is a high current, fast response regulator which
can maintain output voltage regulation with minimum input to
output voltage drop. Fabricated on a CMOS process, the
device operates from two input voltages: Vbias provides
voltage to drive the gate of the N-MOS power transistor,
while Vin is the input voltage which supplies power to the
load. The use of an external bias rail allows the part to
operate from ultra low Vin voltages. Unlike bipolar regula-
tors, the CMOS architecture consumes extremely low quies-
cent current at any output load current. The use of an
N-MOS power transistor results in wide bandwidth, yet mini-
mum external capacitance is required to maintain loop sta-
bility.
The fast transient response of these devices makes them
suitable for use in powering DSP, Microcontroller Core volt-
ages and Switch Mode Power Supply post regulators. The
parts are available in TO-220 and TO-263 packages.
Dropout Voltage:
75 mV (typ)
@
0.8A load current.
Ground Pin Current:
3 mA (typ) at full load.
Shutdown Current:
60 nA (typ) when S/D pin is low.
Precision Output Voltage:
1.5% room temperature accu-
racy.
Features
n
n
n
n
n
n
n
n
Ultra low dropout voltage (75 mV
@
0.8A typ)
Low ground pin current
Load regulation of 0.04%/A
60 nA typical quiescent current in shutdown
1.5% output accuracy (25藲C)
TO-220, TO-263 packages
Over temperature/over current protection
鈭?0藲C to +125藲C junction temperature range
Applications
n
n
n
n
n
n
n
DSP Power Supplies
Server Core and I/O Supplies
PC Add-in-Cards
Local Regulators in Set-Top Boxes
Microcontroller Power Supplies
High Efficiency Power Supplies
SMPS Post-Regulators
Typical Application Circuit
20063001
At least 4.7 碌F of input and output capacitance is required for stability.
Connection Diagrams
20063002
20063003
TO-220, Top View
TO-263, Top View
漏 2003 National Semiconductor Corporation
DS200630
www.national.com