SC1155_01 Datasheet, PDF (1/20 Pages) Semtech Corporation – Programmable Synchronous DC/DC Hysteretic Controller with VRM 9.0VID Range

SC1155
Programmable Synchronous DC/DC
Hysteretic Controller with VRM 9.0 VID Range
POWER MANAGEMENT
Description
.eatures
PRELIMINARY
The SC1155 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 SC1155 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.
SC1155 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 MOS.ET 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.
K Programmable hysteresis
K 5 bit DAC programmable output (1.1V-1.85V)
K On-chip power good and OVP functions
K Designed to meet latest Intel specifications
K Up to 95% efficiency
K +1% tolerance over temperature
Applications
K Server Systems and Workstations
K Pentium^® III Core Supplies
K AMD Athlon^® Core Supplies
K Multiple Microprocessor Supplies
K Voltage Regulator Modules
The SC1155 high side driver can be configured as either
a ground-referenced or as a floating bootstrap driver.
The high and low side MOS.ET drivers have a peak cur-
rent rating of 2 amps.
Typical Application Circuit
+5V
R2
1k
R4
1k
R1
*
R9
U1
10k
R3
SC1155
*
1 _IOUT
PWRGD ²⁸
2 _DROOP
VID0 ²⁷
3 _OCP
VID1 ²⁶
R5
*
R6
20k
C2
0.001
4 _VHYST
5 _VREFB
C1
0.1
6 _VSENSE
7 _AGND
VID2 ²⁵
VID3 ²⁴
VID4 ²³
INHIBIT ²²
R10
1k
R11
1k
PWRGD
"POWER GOOD"
C6
0.1
INHIB
"INHIBIT"
C7
0.1
L1
0.5uH
Cin
H.
Cin
Bulk
8 _SOFTST
IOUTLO ²¹
C3
+5V
0.1
9 _N/C
LOSENSE ²⁰
C8
0.033
C4
0.01
10 _LODRV
HISENSE ¹⁹
11 _LOHIB
12 _DRVGND
BOOTLO ¹⁸
HIGHDR ¹⁷
Q1
.DB6035AL
R12
1.0
13 _LOWDR
14 _DRV
C5
BOOT ¹⁶
L2
1.0uH
+12V
C9
1.0
VIN12V ¹⁵
Q2
.DB7030BL
R14
1.6
Cout
Cout
Bulk
H.
C10
+
Vin +5V/12V
_
+
1.10 to 1.825V
_
R7
R8 *
10k
*) for the values see specific application circuit somewhere else in the datasheet
Revision 2, June 2001
1
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