LP38851 Datasheet, PDF (1/18 Pages) National Semiconductor (TI) – 800 mA Fast-Response High-Accuracy Adjustable LDO Linear Regulator with Enable and Soft-Start

June 2007
LP38851
800 mA Fast-Response High-Accuracy Adjustable LDO
Linear Regulator with Enable and Soft-Start
General Description
The LP38851-ADJ 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 pro-
cess, the device operates from two input voltages: V_BIAS
provides voltage to drive the gate of the N-MOS power tran-
sistor, 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 minimum ex-
ternal 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 part is avail-
able in PSOP 8–pin, TO-220 7–pin, and TO-263 7-pin pack-
ages.
Dropout Voltage: 115 mV (typical) at 800 mA load current.
Low Ground Pin Current: 10 mA (typical) at 800 mA load
current.
Soft-Start: Programmable Soft-Start time.
Precision ADJ Voltage: ±1.5% for T_J = 25°C, and ±2.0% for
0°C ≤ T_J ≤ +125°C, across all line and load conditions
Features
■ ^{Adjustable V}_OUT ^{range of 0.80V to 1.8V}
■ ^{Wide V}_BIAS ^{Supply operating range of 3.0V to 5.5V}
■ ^{Stable with 10µF Ceramic capacitors}
■ ^{Dropout voltage of 115 mV (typical) at 800 mA load current}
■ ^{Precision V}_ADJ ^{across all line and load conditions:}
— ±1.5% V_ADJ for T_J = 25°C
— ±2.0% V_ADJ for 0°C ≤ T_J ≤ +125°C
— ±3.0% V_ADJ for -40°C ≤ T_J ≤ +125°C
■ ^{Over-Temperature and Over-Current protection}
■ ^{Available in 8 lead PSOP, 7 lead TO-220 and 7 lead}
TO-263 packages
■ ^{−40°C to +125°C Operating Junction 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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