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SC2453
High Performance Quad Output
Switching Regulator
POWER MANAGEMENT
Revision: July 20, 2005
Description Features
Applications
Typical Application Circuit
Two synchronized converters for low noise
Power up sequencing to prevent latch-up
Out of phase operation for low input ripple
Over current protection
Wide input range, 4.5 to 30V
Programmable frequency up to 700KHz
Two synchronous bucks for high efficiency at high
current
One dedicated programmable positive linear
regulator and one dedicated programmable
negative linear regulator
Output voltage as low as 0.5V
Small package TSSOP-28. Also offered in lead free,
WEEE and RoHS compliant package
DSL applications with multiple input voltage re-
quirements
Mixed-Signal applications requiring positive and
negative voltages
Cable modem power management
Base station power management
The SC2453 is a high performance controller for multi-
output converters that can be configured for a wide vari-
ety of applications. The SC2453 utilizes PWM synchro-
nous buck topologies where efficiency is most important.
It also provides dedicated programmable positive and
negative linear regulators using external transistors. Each
of the three positive outputs is adjustable down to 0.5V.
The two PWM switchers are synchronized 180° out of
phase reducing input ripple, allowing for fewer input ca-
pacitors. Power up sequencing prevents converter latch-
up.
The SC2453 can be synchronized to other converters to
prevent beat frequencies. The wide range programmable
operating frequency allows users to optimize a converter
design. The PWM switchers sense the voltage across the
low-side MOSFETs on-resistance to efficiently provide
adjustable current-limit, eliminating costly current-sense
resistors. A POK signal is issued when soft-start is com-
plete on both PWM switchers and their outputs are within
10% of the set point.
R8
C8
R14
R16
C1
R18
C5
C7
D1
Q1
C12
C3
R6
R5
C14
L2
C2
R17
Q4
D3
R11
C13
R7
Q6
C20
C10
C16
C15
C18
R4
C11
C19
C6
C17
C9
Q3
R3
Vout2: +3.3V
Vout1: +5V
Vout3: -12V
Vout4: +2.5V
R1
(as low as 0.5V)
(as low as 0.5V)
Vin: 4.5 - 30V
To Vout2
To Vout2
Q7
R9
Q5
D2
L1
R10
Q2
GD1L
23
PH1
24
GD1H
25
EO2
12
BS T1
26
POK
8
SYNC
7
AGND
15
EO1
3
GD2L
20
FB1
2
BD4
4
FB2
13
PH2
19
GD2H
18
BS T2
17
FB4
5
BDI
28
ILI M2
14
VIN
27
PGND
21
ILI M1
1
BD3
11
FB3
10
PVCC
22
AVCC
16
SS/SHDN
6
OSC
9
SC 24 53
R12
R15
R13
C4
