POWER MANAGEMENT

1

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SC2621

500kHz Voltage Mode PWM Controller

With Linear Power Regulator

Features

Applications

December 17, 2004

Typical Application Circuit

Description

The SC2621 provides the control and protection features

necessary for a synchronous buck converter and a lin-

ear regulator in high performance graphic card applica-

tions.

The SC2621 is designed to directly drive the top and

bottom MOSFETs of the buck converter. It uses an inter-

nal 8.2V supply as the gate drive voltage for minimum

driver power loss and MOSFET switching loss. It allows

the converter to operate at 500kHz switching frequency

with 4V to 16V power rail and as low as 0.5V output. The

SC2621 is capable to drive a N-type MOSFET in a linear

regulator with as low as 0.5V output.

The SC2621 features soft-start, supply power under volt-

age lockout, and hiccup mode over current protection.

The SC2621 monitors the output current by using the

Rdson of the bottom MOSFET in the buck converter that

eliminates the need for a current sensing resistor. The

SC2621 is offered in a SOIC-14 package.

platform

1.5V OUT

+

+

1

2

2.5V OUT

3.3V IN

+

12V IN

SC2621

1

2

3

4

10

11

12

14

5

13

6

7

9

8

PN

LDOG

LDFB

OCS

DL

DRV

BST

DH

FB

NC

COMP

NC

GND

VCC