POWER MANAGEMENT

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SC4508

Buck or Buck-Boost(Inverting)

Current Mode Controller

Description

Revision: November 30, 2004

Features

Typical Application Circuits

Applications

Wide input voltage range 2.7V to 15V

Programmable output voltage

Programmable switching frequency up to 1.5MHz

Buck or buck boost(inverting) configuration

Current mode control with slope compensation

Very low quiescent current in shutdown mode

Accessible reference voltage

MLPQ-12 package

Low power point of use converters

Single or multiple output low power converters

Positive and/or negative output voltage

DSL cards

Graphic cards

I/O cards

Negative bias supplies

The SC4508 is a low voltage current mode switching regu-

lator controller that drives a P-channel power MOSFET

with programmable switching frequency. It can be con-

figured in either buck or buck boost (inverting) convert-

ers. The converters can be operated from 2.7V to 15V

input voltage range. The typical operating supply current

is 3mA and a shutdown pin allows the user to turn the

voltage can adjusted by external resistor divider. The

switching frequency is programmable up to 1.5MHz,

allowing small inductor and capacitor values to minimize

PCB space. The operating current level is programmable

via an external sense resistor. Accessible reference volt-

age allows users to make output voltage as low as they

want.

VREF

CS

OUT

VDD

FB+

FB-

COMP

SS/SHDN

OSC

SC4508

Vin

GND

CS

OSC

VDD

Vin

SS/SHDN

FB-

GND

SC4508

OUT

FB+

VREF

COMP