SC2655
Programmable Synchronous DC/DC
Hysteretic Controller with VRM 9.0 VID Range
POWER MANAGEMENT
Features
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
such as Pentium® llI and Athlon®, in both single and mul-
tiple processor configurations. Inhibit, under-voltage lock-
out and soft-start functions are included for controlled
power-up.
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
Applications
Server Systems and Workstations
Pentium® III Core Supplies
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.
AMD Athlon® Core Supplies
Multiple Microprocessor Supplies
Voltage Regulator Modules
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.
Typical Application Circuit
+5V
R1
*
R10
1k
R9
10k
U1
SC2655
R3
*
PWRGD
1
2
28
27
26
25
24
23
22
21
20
19
18
17
16
15
IOUT
PWRGD
VID0
"POWER GOOD"
R2
1k
C6
0.1
DROOP
OCP
R4
1k
INHIB
3
VID1
"INHIBIT"
C7
0.1
R11
1k
4
VHYST
VREFB
VSENSE
AGND
SOFTST
N/C
VID2
R5
*
5
VID3
L1
0.5uH
C1
0.1
R6
20k
6
+
VID4
C2
0.001
Cin
HF
Cin
Bulk
7
Vin +5V/12V
INHIBIT
IOUTLO
LOSENSE
HISENSE
BOOTLO
HIGHDR
BOOT
8
_
C8
0.033
C3
0.1
9
+5V
10
11
12
13
14
LODRV
LOHIB
DRVGND
LOWDR
DRV
C4
0.01
Q1
FDB6035AL
R12
1.0
L2
1.0uH
C9
1.0
+12V
+
Q2
VIN12V
FDB7030BL
R14
1.6
Cout
Bulk
Cout
HF
1.10 to 1.825V
C5
C10
_
R7
*
R8
10k
*) for the values see specific application circuit somewhere else in the datasheet
Revision: December 10, 2003
1
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