POWER MANAGEMENT

1

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SC1189

Programmable Synchronous DC/DC

Converter, Dual LDO Controller

Features

Applications

Revision: July 6, 2005

Description

The SC1189 combines a synchronous voltage mode

controller with two low-dropout linear regulators

providing most of the circuitry necessary to implement

three DC/DC converters for powering advanced

The SC1189 switching section features an integrated 5

bit D/A converter, latched drive output for enhanced noise

immunity, pulse by pulse current limiting and logic

compatible shutdown. The SC1189 switching section

operates at a fixed frequency of 200kHz, providing an op-

timum compromise between size, efficiency and cost in

the intended application areas. The integrated D/A con-

verter provides programmability of output voltage from

1.05V to 1.825V in 25mV increments with no external

components.

The SC1189 linear sections are low dropout regulators

with short circuit protection, supplying 1.25V for Vtt and

2.5V for non-GTL I/O. They can be easily adjusted to sup-

ply higher voltages e.g. 1.8V chipset.

·Synchronous design, enables no heatsink solution

95% efficiency (switching section)

5 bit DAC for output programmability

1.25V, 2.5V short circuit protected linear controllers

Linear controllers adjustable to 1.8V chipset.

VRM 8.5 Compliant

VRM 8.4 Compliant (1.3V to 1.8V)

1.0% accuracy (1.6V to 1.8V)

On Chip Power Good Signal

1.050V to 1.825V microprocessor supplies

Programmable triple power supplies

3.3V

0.1uF

EN

10

x4

+

1500uF

U6

SC1189CS

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

PWRGD

LDOEN

CS-

CS+

PGNDH

DH

BSTH

EN

VOSENSE

VID3

VID2

VID1

VID0

VID25MV

DL

PGNDL

BSTL

GATE2

GATE1

LDOV

LDOS1

LDOS2

2R2

+

330uF

+

1500uF

+

330uF

442

2.5V

2.5mOhm

2R2

VID2

1k

0.1uF

VID3

1.0k

OPEN

PWRGD

VID25MV

0.1uF

x6

10k

VID0

5V

VID1

12V

5V

1.00k

1.8V

VCC_CORE

0.1uF

+

47uF

+

330uF

1.2uH

0.1uF

Simplified Application Circuit