SC339 Datasheet, PDF (1/15 Pages) Semtech Corporation – Ultra Low Output Voltage Linear FET Controller

POWER MANAGEMENT
Description
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
LDO^TM family of products. The SC339 has a user
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.
Typical Application Circuit
1.2V +/-5% IN
SC339
Ultra Low Output Voltage
Linear FET Controller
Features
± 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
Applications
Notebook PCs
Desktop Computers
Battery Powered Devices
Portable Instruments
IRF7311
C1
or similar
5V IN
1.05V
Enable
IN
DRV
GND SC339 _ADJ
EN
PGD
1.05V
Power Good
R3 ⁽¹⁾
C4
Notes:
(1) Optional Components to use with ceramic output
capacitors (C2)
C3 ⁽¹⁾
V_out = (1+R1/R2)*0.5
1.05V @ 3A
C2
R1
R2
Sept 11, 2006
1
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