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SC339

Ultra Low Output Voltage

Linear FET Controller

POWER MANAGEMENT

Sept 11, 2006

Description

Features

The SC339 is an ultra-low output voltage, linear power

supply controller designed to simplify power manage-

ment for notebook PCs. It is part of Semtech’s Smart

adjustable output that can be set anywhere between 0.5V

and 3.3V using two external resistors.

SC339 features include tight output voltage regulation (±

1% over 0°C to +85°C), enable control, open drain power

good signal, under-voltage protection and soft-start. The

enable pin allows the part to enter a very low power standby

mode. Pulling it high enables the output. The power good

pin is an open drain and asserts low when the voltage at

the adjust pin is below 88% (typ) of nominal. If the voltage

at the adjust pin is below 50% (typ) of nominal, the under-

voltage protection circuitry will shut down the output. The

SC339 is available in a tiny SOT-23 6-pin surface mount

package.

± 1% Voltage Accuracy Over-Temperature

Low Shutdown Current

Runs Off 5V Supply

Ultra-Fast Transient Response

Enable Control for the Output

Power Good Monitoring and Signaling for the Output

Gate Drive from Input Supply Enables Use of

N-Channel MOSFET

User Selectable Dropout Voltage

Under-Voltage Protection for the Output

SOT-23 6-pin Surface Mount Package

Compatible with Ceramic Capacitors

Low Ripple Output

Internal 1ms soft-start requires no external compo-

nents

Fully WEEE and RoHS compliant

Notebook PCs

Desktop Computers

Battery Powered Devices

Portable Instruments

Typical Application Circuit

Applications

1.05V @ 3A

SC339

IN

DRV

ADJ

PGD

EN

GND

C1

C2

C4

5V IN

1.05V

Enable

1.05V

Power Good

1.2V +/-5% IN

IRF7311

or similar

Notes:

(1) Optional Components to use with ceramic output

capacitors (C2)

R1

R2