Programmable Synchronous DC/DC
Converter, Dual LDO Controller
POWER MANAGEMENT
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
microprocessors such as Pentium
®
III.
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.
SC1189
Features
·Synchronous design, enables no heatsink solution
95% efficiency (switching section)
5 bit DAC for output programmability
Designed for Intel Pentium
®
III requirements
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
Available in Lead free package, fully WEEE and
RoHS compliant.
Applications
Pentium
®
III microprocessor supplies
1.050V to 1.825V microprocessor supplies
Programmable triple power supplies
Simplified Application Circuit
12V
+
5V
47uF
0.1uF
+
1500uF
x4
10
U6
5
VCC
LDOEN
VID25MV
VID0
VID1
VID2
VID3
EN
AGND
LDOV
GATE2
LDOS2
CS+
CS-
VOSENSE
BSTH
DH
BSTL
DL
PGNDH
PGNDL
PWRGD
GATE1
LDOS1
9
8
17
15
11
14
13
10
12
6
2
3
10k
PWRGD
5V
1k
1500uF
x6
0.1uF
VID25MV
VID0
VID1
VID2
VID3
EN
7
22
21
20
19
18
16
1
23
24
4
0.1uF
0.1uF
2R2
1.00k
OPEN
2.5mOhm
1.2uH
2R2
+
0.1uF
VCC_CORE
SC1189CS
3.3V
+
330uF
+
330uF
442
1.0k
1.8V
2.5V
+
330uF
Revision: November 1, 2007
1
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