POWER MANAGEMENT

1

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SC1185 & SC1185A

Programmable Synchronous DC/DC

Converter, Dual LDO Controller

Features

Applications

Revision: July 28, 2005

Description

The SC1185 combines a synchronous voltage mode con-

troller with two low-dropout linear regulators providing

most of the circuitry necessary to implement three DC/

DC converters for powering advanced microprocessors

The SC1185 switching section features an integrated 5

bit D/A converter, pulse by pulse current limiting, inte-

grated power good signaling, and logic compatible shut-

down. The SC1185 switching section operates at a fixed

frequency of 140kHz, providing an optimum compromise

between size, efficiency and cost in the intended appli-

cation areas. The integrated D/A converter provides pro-

grammability of output voltage from 2.0V to 3.5V in

100mV increments and 1.30V to 2.05V in 50mV incre-

ments with no external components.

The SC1185 linear sections are low dropout regulators

supplying 1.5V for GTL bus and 2.5V for non-GTL I/O.

The Reference voltage is made available for external lin-

ear regulators.

Synchronous design, enables no heatsink solution

95% efficiency (switching section)

5 bit DAC for output programmability

On chip power good function

1.5V, 2.5V @ 1.25% for linear section

1.265V ± 1.5% Reference available

24-lead SO package. Lead free option available.

Lead free product is fully WEEE and RoHS

compliant.

Flexible motherboards

1.3V to 3.5V microprocessor supplies

Programmable triple power supplies

Typical Application Circuit

1.00k

PWRGOOD

2.5V

+

1500uF

2R2

IRLR3103N

+

330uF

1k

VLIN3

x4

0.1uF

1.9uH

+

330uF

VID3

3.3V

SC1185CS

1

5

6

7

8

9

10

11

15

16

17

18

19

20

21

22

13

12

14

24

2

23

3

4

AGND

VCC

REF

PWRGOOD

CS-

CS+

PGNDH

DH

BSTH

EN

VOSENSE

VID4

VID3

VID2

VID1

VID0

DL

PGNDL

BSTL

GATE2

GATE1

LDOV

LDOS1

LDOS2

+

330uF

VID1

VID0

VID2

+

330uF

2.32k

0.1uF

IRLR024N

+

1500uF

5V

+

4.7uF

1.5V

VID4

x6

5mOhm

IRLR024N

EN

0.1uF

VCC_CORE

2R2

12V

IRLR024N

3.3V

0.1uF

12V

IRLR3103N

10

+

-

LM358

3

2

1

8

4