Programmable Synchronous DC/DC
Converter, Dual LDO Controller
POWER MANAGEMENT
Description
The SC2688 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
廬
III.
The SC2688 switching section features latched drive out-
put for enhanced noise immunity, pulse by pulse current
limiting and logic compatible shutdown. The SC2688
switching section operates at a fixed frequency of 140kHz,
providing an optimum compromise between size, efficiency
and cost in the intended application areas.
The SC2688 linear sections are low dropout regulators
with short circuit protection, supplying 1.5V for GTL bus
and 2.5V for non-GTL I/O.
SC2688
Features
路Synchronous design, enables no heatsink solution
95% efficiency (switching section)
Designed for embedded Pentium
廬
III requirements
1.5V, 2.5V short circuit protected linear controllers
Applications
Embedded Pentium
廬
III microprocessor supplies.
Typical Application Circuit
12V
+
5V
+
1500uF
x4
47uF
0.1uF
10
11
4
BST
VCC
LDOEN
EN
AGND
LDOV
GATE2
LDOS2
CS+
CS-
DH
DL
FB
PGND
GATE1
LDOS1
7
6
8
10
13
9
1
2
0.1uF
0.1uF
2R2
2R2
1.00k
1.9uH
2.32k
VCC_CORE
5mOhm
EN
0.1uF
5
12
16
14
15
3
+
0.1uF
SC2688S
3.3V
1k
+
330uF
+
330uF
330uF
+
1.5V
2.5V
1500uF
x6
Revision: March 25, 2004
1
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