POWER MANAGEMENT

1

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SC1102/SC1102A

Synchronous Voltage Mode Controller

for Distributed Power Supply Applications

Features

Applications

Revision: January 5, 2006

Typical Application Circuit

Description

1.265V reference available

Synchronous operation for high efficiency (95%)

R

On-chip power good and OVP functions

Small size with minimum external components

Soft Start

Enable function

14 Pin SOIC lead free package available. Fully

WEEE and RoHS compliant

Microprocessor core supply

Low cost synchronous applications

Voltage Regulator Modules (VRM)

DDR termination supplies

Networking power supplies

Sequenced power supplies

The SC1102 and SC1102A are low-cost, full featured,

synchronous voltage-mode controllers designed for use

in single ended power supply applications where efficiency

is of primary concern. Synchronous operation allows for

the elimination of heat sinks in many applications. The

SC1102s are ideal for implementing DC/DC converters

needed to power advanced microprocessors in low cost

systems, or in distributed power applications where effi-

ciency is important. Internal level-shift, high-side drive

circuitry, and preset shoot-thru control, allows the use of

inexpensive N-channel power switches.

SC1102s features include temperature compensated

voltage reference, triangle wave oscillator and current

sense comparator circuitry. Power good signaling, shut-

down, and over voltage protection are also provided.

The SC1102 operates at a fixed frequency of 200kHz

and the SC1102A at 500kHz, providing a choice for op-

timum compromise between efficiency, external compo-

nent size, and cost.

Two SC1102s can be used together to sequence power

up of telecom systems. The power good of the first

SC1102 connected to the enable of the second SC1102

makes this possible.

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Figure 1.

VCC

1

PWRGD

2

OVP

3

OCSET

4

PHASE

5

DRVH

6

PGND

7

DRVL

8

BSTL

9

BSTH

10

SENSE

11

VREF

12

SS/SHDN

13

GND

14

U1

SC1102

Q1

STP40NE

Q2

STP40NE

R5

3.9

L1

2uH

C9

180/4V

C10

180/4V

C11

180/4V

C12

180/4V

C7

680/6.3V

C6

680/6.3V

R1

1k

R3

1k

C2

0.1

C3

0.1

C1

opt.

R2

PWRGD

OVP

SHDN

VREF

+

_

+

_

Vin 5V

Vout=2.5V*

R7

127

R8

124*

NOTE:

*) Vout = 1.265 x (1+R8/R7)

+5V

D1

MBR0520

R6

2.2

C4

1.0

C5

10.0

C8

680/6.3V

R4

10

+12V

C13

180/4V

0.1