SYNCHRONOUS PWM CONTROLLER WITH

DUAL LOW DROPOUT REGULATOR

CONTROLLERS

© 2000 SEMTECH CORP.

PRELIMINARY - October 16, 2000

SC1109

1

TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com

DESCRIPTION

The SC1109 was designed for the latest high

speed motherboards. It combines a synchronous

voltage mode controller (switching section) with

two low-dropout linear regulator controllers. The

voltage mode controller provides the power

supply for the system AGTL bus. The 1.8V and

2.5V linear controllers power the Chipset and

clock circuitry.

The SC1109 switching section features lossless

current sensing and latched driver outputs for

enhanced noise immunity. It operates at a fixed

frequency of 200kHz, the output voltage is

internally fixed at 1.2V

The SC1109 linear sections are low dropout

regulators designed to track the 3.3V power

supply when it turns on or off.

Pentium is a registered trademark of Intel Corporation

FEATURES

regulation

APPLICATIONS

ORDERING INFORMATION

Part Number

(1)

Package

Linear

Voltage

Temp.

Range (T

SC1109CSTR

SO-16

1.8V/2.5V 0° to 125°C

SC1109EVB

Evaluation Board

Note:

(1) Only available in tape and reel packaging. A reel

contains 1000 devices.

Q2

C1

0.1uF

L1

4uH

POWER GOOD

Q4

C6

0.1uF

Q3

C9

0.1uF

C8

0.1uF

+

C12

330uF

+

C2

2x1500uF

5V IN

+

C7

3x1500uF

2.5V

C4

0.1uF

5V STBY

C3

0.1uF

+

C11

330uF

VTT

+

C10

330uF

U4

SC1109CS

13

5

3

7

6

8

10

12

14

4

11

9

15

1

2

16

PWRGD

BCAP-

STBY

PHASE

GND

DH

BST

VOSENSE

SS/EN

BCAP+

VCC

DL

GATE2

GATE1

LDOS1

LDOS2

1.2V 6A

C5

0.1uF

3.3V IN

R1 2.2

1.8V

Q1

12V IN

R2 2.2

TYPICAL APPLICATION CIRCUIT