1

www.semtech.com

SC4611

Wide Input Range High Performance

Synchronous Buck Switching Regulator

POWER MANAGEMENT

Revision: November 10, 2004

Description

Features

Applications

Typical Application Circuit

Wide input range, 4.5 to 30V

Output voltage as low as 0.5V

2A output drive capability

Asynchronous start up mode

Multimode overcurrent protection with current limit,

hiccup mode and latched shutdown

Overvoltage crowbar protection

Power OK signal

Programmable frequency up to 1 MHz with external

synchronization

–40 to +85 degree C operating temperature

Thermal shutdown

Small package TSSOP-20

SC4611 is a high performance synchronous buck controller

that can be configured for a wide range of applications.

The SC4611 utilizes synchronous rectified buck topologies

where high efficiency is the primary consideration. It is

optimized for applications involving multiple and redundant

convertors connected together. The startup is

asynchronous, which keeps the lower side FET off during

soft start. This is a desired feature when a convertor is

turned on with a preset external voltage or pre-bias voltage

already present across its output. With the lower FET off,

external bus is not discharged which avoids latch-up of

modern ASIC circuits.

SC4611 comes with a rich set of features like regulated

Vcc supply, soft start, power-good signaling, high current

gate drivers, bootstrapped supply for driving high side N-

channel MOSFETs, shoot through protection, frequency

synchronization and the option for overvoltage crowbar. It

also features multi mode overload protection that includes

continuous current limiting, hiccup mode followed by latch

off. The user has the option of bypassing the hiccup mode

and latch off the output if required.

Distributed power architectures

Telecommunication equipment

Servers/work stations

Mixed signal applications

Paralleled synchronous buck convertors

Base station power management

Cin

Cout

Rcs

Rclset

RT

QH

QL

Lout

VIN

4

AVC C

17

PVCC

20

PGN D

18

GDL

19

PH

1

GDH

2

BS T

3

AG ND

15

EAO

9

FB

8

SS /S H

14

SYNC

16

OS C

13

OVP

11

BD I

5

POK

10

CS +

7

CS -

6

CL M

12

VIN (30V MAX)

VOUT (0.5V MIN)

RTN

RTN