LP38859 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – 3A Fast-Response High-Accuracy LDO Linear Regulator with Soft-Start

June 2006
LP38859
3A Fast-Response High-Accuracy LDO Linear Regulator
with Soft-Start
General Description
The LP38859 is a high current, fast response regulator
which can maintain output voltage regulation with extremely
low input to output voltage drop. Fabricated on a CMOS
process, the device operates from two input voltages: V_BIAS
provides voltage to drive the gate of the N-MOS power
transistor, while V_IN 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 V_IN voltages. Unlike bipolar
regulators, the CMOS architecture consumes extremely low
quiescent 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 this device makes it suitable
for use in powering DSP, Microcontroller Core voltages and
Switch Mode Power Supply post regulators. The LP38859 is
available in TO-220 and TO-263 5-Lead packages.
Dropout Voltage: 240 mV (typical) at 3A load current.
Low Ground Pin Current: 14 mA (typical) at 3A load cur-
rent.
Soft-Start: Programmable Soft-Start time.
Precision Output Voltage: ±1.0% for T_J = 25˚C and ±2.0%
for 0˚C ≤ T_J ≤ +125˚C, across all line and load conditions
Features
n Standard V_OUT values of 0.8V and 1.2V
n Stable with 10µF Ceramic capacitors
n Dropout voltage of 240 mV (typical) at 3A load current
n Precision Output Voltage across all line and load
conditions:
— ±1.0% V_OUT for T_J = 25˚C
— ±2.0% V_OUT for 0˚C ≤ T_J ≤ +125˚C
— ±3.0% V_OUT for -40˚C ≤ T_J ≤ +125˚C
n Over-Temperature and Over-Current protection
n Available in 5 lead TO-220 and TO-263 packages
n Custom V_OUT values between 0.8V and 1.2V are
available
n −40˚C to +125˚C Operating Temperature Range
Applications
n ASIC Power Supplies In:
- Desktops, Notebooks, and Graphics Cards, Servers
- Gaming Set Top Boxes, Printers and Copiers
n Server Core and I/O Supplies
n DSP and FPGA Power Supplies
n SMPS Post-Regulator
Typical Application Circuit
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