SC1155 Datasheet, PDF (1/19 Pages) Semtech Corporation – PROGRAMMABLE SYNCHRONOUS DC/DC HYSTERETIC CONTROLLER WITH VRM 9.0 VID RANGE

PROGRAMMABLE SYNCHRONOUS
DC/DC HYSTERETIC CONTROLLER
WITH VRM 9.0 VID RANGE
SC1155
PRELIMINARY - August 7, 2000
DESCRIPTION
The SC1155 is a synchronous-buck switch-mode con-
troller designed for use in single ended power supply
applications where efficiency is the primary concern.
The controller is a hysteretic type, with a user se-
lectable hysteresis. The SC1155 is ideal for implement-
ing DC/DC converters needed to power advanced mi-
croprocessors such as Pentium^® llI and Athlon^®, in both
single and multiple processor configurations. Inhibit,
under-voltage lockout and soft-start functions are in-
cluded 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 MOSFET during switching transitions.
Power good signaling, logic compatible shutdown, and
over-voltage protection are also provided. The inte-
grated D/A converter provides programmability of out-
put voltage from 1.1V to 1.85V in 25mV increments.
The SC1155 high side driver can be configured as
either a grounded reference or as a floating bootstrap
driver. The high and low side MOSFET drivers have a
peak current rating of 2 amps.
TYPICAL APPLICATION CIRCUIT
FEATURES
•= 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
•= +1% voltage tolerance over temperature
APPLICATIONS
•= Server Systems and Workstations
•= Intel Pentium^® III Core Supplies
•= AMD Athlon^® Core Supplies
•= Multiple Microprocessor Supplies
•= Voltage Regulator Modules
ORDERING INFORMATION
DEVICE⁽¹⁾
PACKAGE TEMP. RANGE (T_J)
SC1155CSW.TR SO-28
0 - 125°C
SC1155EVB
Evaluation Board
Note:
(1) Only available in tape and reel packaging. A reel
contains 1000 devices.
R1 R3
2k 2.7k
R2
1k
R4
1k
C3
0.01
C2
0.01
R5
100
C4
R6
0.01
20k
1 _IOUT
U1
SC1155CSW
PWRGD ²⁸
2 _DROOP
VID0 ²⁷
3 _OCP
VID1 ²⁶
4 _VHYST
VID2 ²⁵
5 _VREFB
C6
0.1
6 _VSENSE
VID3 ²⁴
VID4 ²³
R9
10k
+5V
R10
10k
C5
0.001
7 _AGND
INHIBIT ²²
C12
8 _SOFTST
IOUTLO ²¹
C7
0.33
0.1
C8
+5V
9 _N/C
LOSENSE ²⁰
0.01
10 _LODRV
HISENSE ¹⁹
11 _LOHIB
BOOTLO ¹⁸
R8
12 _DRVGND
HIGHDR ¹⁷
R11
2.2
Q1
IRL3103S
10k
C13
13 _LOWDR
BOOT ¹⁶
0.33
+12V
14 _DRV
VIN12V ¹⁵
Q2
R12 IRL2203S
3.9
C8
2.2uF
C9
2.2uF
R7
150
PWRGD
INHIB
L1
1uH
C16
0.1
C17-C19
150uF/16V
Vin
C20
0.1 Vin +5 to +12V
GND
L2
1.5uH
Vout
C21-C26
150uF/4V
C27
0.1 Vout = 1.1 to 1.85V
GND
© 2000 SEMTECH CORP.
Athlon is a registered trademark of AMD Corporation
1
Pentium is a registered trademark of Intel Corporation
TEL:[phone] FAX:[phone] WEB:http://www.semtech.com