LP38858 Datasheet, PDF (1/14 Pages) National Semiconductor (TI) – 1.5A Fast-Response High-Accuracy LDO Linear Regulator with Soft-Start

November 2006
LP38858
1.5A Fast-Response High-Accuracy LDO Linear Regulator
with Soft-Start
General Description
The LP38858 is a high current, fast response regulator which
can maintain output voltage regulation with extremely low in-
put 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 archi-
tecture consumes extremely low quiescent current at any
output load current. The use of an N-MOS power transistor
results in wide bandwidth, yet minimum external capacitance
is required to maintain loop stability.
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 LP38858 is
available in TO-220 and TO-263 5-Lead packages.
Dropout Voltage: 130mV (typical) at 1.5A load current.
Low Ground Pin Current: 14 mA (typical) at 1.5A 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
■ ^{Standard V}_OUT ^{values of 0.8V and 1.2V}
■ ^{Wide V}_BIAS ^{Supply operating range of 3.0V to 5.5V}
■ ^{Stable with 10µF Ceramic capacitors}
■ ^{Dropout voltage of 130 mV (typical) at 1.5A load current}
■ ^{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
■ ^{Over-Temperature and Over-Current protection}
■ ^{Available in 5 lead TO-220 and TO-263 packages}
■ ^{Custom V}_OUT ^{values between 0.8V and 1.2V are available}
■ ^{−40°C to +125°C Operating Temperature Range}
Applications
■ ^{ASIC Power Supplies In:}
- Desktops, Notebooks, and Graphics Cards, Servers
- Gaming Set Top Boxes, Printers and Copiers
■ ^{Server Core and I/O Supplies}
■ ^{DSP and FPGA Power Supplies}
■ ^{SMPS Post-Regulator}
Typical Application Circuit
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