POWER MANAGEMENT

1

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SC2655

Programmable Synchronous DC/DC

Hysteretic Controller with VRM 9.0 VID Range

Features

Applications

Revision: December 10, 2003

Description

The SC2655 is a synchronous-buck switch-mode con-

troller designed for use in single ended power supply ap-

plications where efficiency is the primary concern. The

controller is a hysteretic type, with a user selectable hys-

teresis. The SC2655 is ideal for implementing DC/DC

converters needed to power advanced microprocessors

tiple processor configurations. Inhibit, under-voltage lock-

out and soft-start functions are included for controlled

power-up.

SC2655 features include an integrated 5 bit D/A con-

verter, temperature compensated voltage reference,

current limit comparator, over-current protection, and an

adaptive deadtime circuit to prevent shoot-through of

the power MOSFET during switching transitions. Power

good signaling, logic compatible shutdown, and over-volt-

age protection are also provided. The integrated D/A

converter provides programmability of output voltage

from 1.1V to 1.85V in 25mV increments.

The SC2655 high side driver can be configured as either

a ground-referenced or as a floating bootstrap driver.

The high and low side MOSFET drivers have a peak cur-

rent rating of 2 amps.

Server Systems and Workstations

Multiple Microprocessor Supplies

Voltage Regulator Modules

Programmable hysteresis

5 bit DAC programmable output (1.1V-1.85V)

On-chip power good and OVP functions

Designed to meet latest Intel specifications

Up to 95% efficiency

VIDs pulled up to +3.3V

Typical Application Circuit

R12

1.0

R14

1.6

L2

1.0uH

R3

*

R1

*

R4

1k

R2

1k

R5

*

R6

20k

R7

*

R8

10k

C5

C10

+12V

C8

0.033

R10

1k

+5V

R9

10k

+5V

C7

0.1

C1

0.1

Cin

Bulk

L1

0.5uH

PWRGD

INHIB

"POWER GOOD"

"INHIBIT"

+

_

Vin +5V/12V

1.10 to 1.825V

+

_

C9

1.0

Q1

FDB6035AL

Q2

FDB7030BL

Cout

Bulk

C4

0.01

R11

1k

C6

0.1

Cin

HF

Cout

HF

C2

0.001

C3

0.1

*) for the values see specific application circuit somewhere else in the datasheet

IOUT

1

DROOP

2

OCP

3

VHYST

4

VREFB

5

VSENSE

6

AGND

7

SOFTST

8

N/C

9

LODRV

10

LOHIB

11

DRVGND

12

LOWDR

13

DRV

14

VIN12V

15

BOOT

16

HIGHDR

17

BOOTLO

18

HISENSE

19

LOSENSE

20

IOUTLO

21

INHIBIT

22

VID4

23

VID3

24

VID2

25

VID1

26

VID0

27

PWRGD

28

U1

SC2655