SC2453_05 Datasheet, PDF (1/22 Pages) Semtech Corporation – High Performance Quad Output Switching Regulator

POWER MANAGEMENT
Description
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.
Typical Application Circuit
SC2453
High Performance Quad Output
Switching Regulator
Features
‹ 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
Applications
‹ DSL applications with multiple input voltage re-
quirements
‹ Mixed-Signal applications requiring positive and
negative voltages
‹ Cable modem power management
‹ Base station power management
Vin: 4.5 - 30V
Q1 ^R1
C2
C1
C3
R3
C4
D1
D2
To Vout2
C6
R4
C9
6 _SS/SHDN
9 _OSC
7 _SYNC
8 _POK
Vout4: +2.5V
Vout3: -12V
R9
C14
R14
C10
Q4
R7
4 _BD4
R10
Q7 ^R11
C17 C18
5 _FB4
11 _BD3
C16
10 _FB3
SC 2453
BS T2 ¹⁷
GD2H ¹⁸
PH2 ¹⁹
GD2L ²⁰
FB2 ¹³
EO2 ¹²
BS T1 ²⁶
GD1H ²⁵
PH1 ²⁴
GD1L ²³
FB1 ²
EO1 ³
C7
R8
C11
C12
C13
C19
Q2
Q3
Q5
Q6
C20
R15
R16 R17
D3
C5
L1
Vout2: +3.3V
C8 ^{R5 (as low as 0.5V)}
R6
L2
Vout1: +5V
C15
(as low as 0.5V)
R12
R13
R18
To Vout2
Revision: July 20, 2005
1
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