POWER MANAGEMENT
1
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SC1189
Programmable Synchronous DC/DC
Converter, Dual LDO Controller
Features
Applications
Revision: November 1, 2007
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.
·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.
Pentium
®
III microprocessor supplies
1.050V to 1.825V microprocessor supplies
Programmable triple power supplies
3.3V
0.1uF
EN
10
x4
+
1500uF
U6
SC1189CS
1
5
6
7 8
9
10
11
15
16
17
18
19
20
21
22
13
12
14
24 2
23
34
AGND
VCC
PWRGD
LDOEN CS-
CS+
PGNDH
DH
BSTH
EN
VOSENSE
VID3
VID2
VID1
VID0
VID25MV
DL
PGNDL
BSTL
GATE2 GATE1
LDOV
LDOS1LDOS2
2R2
+
330uF
+
1500uF
+
330uF
442
2.5V
2.5mOhm
2R2
VID2
1k
0.1uF
VID3
1.0k
OPEN
PWRGD
VID25MV
0.1uF
x6
10k
VID0
5V
VID1
12V
5V
1.00k
1.8V
VCC_CORE
0.1uF
+
47uF
+
330uF
1.2uH
0.1uF
Simplified Application Circuit
