SC4525A
28V 3A Step-Down Switching Regulator
POWER MANAGEMENT
Features
Description
The SC4525A is a constant frequency peak current-mode
step-down switching regulator capable of producing 3A
output current from an input ranging from 8V to 28V. The
switching frequency of the SC4525A is programmable
up to 2MHz, allowing the use of small inductors and
ceramic capacitors for miniaturization, and high input/
output conversion ratio. The SC4525A is suitable for
next generation XDSL modems, high-definition TVs and
various point of load applications.
Peak current-mode PWM control employed in the
SC4525A achieves fast transient response with simple loop
compensation. Cycle-by-cycle current limiting and hiccup
overload protection reduces power dissipation during
output overload. Soft-start function reduces input start-
up current and prevents the output from overshooting
during power-up.
The SC4525A is available in SOIC-8 EDP package.
Wide input range: 8V to 28V
3A Output Current
200kHz to 2MHz Programmable Frequency
Precision V Feedback Voltage
Peak Current-Mode Control
Cycle-by-Cycle Current Limiting
Hiccup Overload Protection with Frequency Foldback
Soft-Start and Enable
Thermal Shutdown
Thermally Enhanced 8-pin SOIC Package
Fully RoHS and WEEE compliant
Applications
XDSL and Cable Modems
Set Top Boxes
Point of Load Applications
CPE Equipment
DSP Power Supplies
LCD and Plasma TVs
SC4525A
Typical Application Circuit
Efficiency
V
IN
10V – 28V
D1
90
80
C4
4.7mF
IN
BST
SW
Efficiency (%)
1N4148
C1
0.1mF
L1
5.2mH
OUT
V
IN
= 12V
70
60
50
40
V
IN
= 24V
SS/EN
SC4525A
FB
R4
33.2k
5V/3A
COMP
ROSC
GND
C7
10nF
C8
10pF
R7
24.3k
C5
1nF
R5
18.2k
D2
20BQ030
R6
8.25k
C2
10mFX3
L1: Coiltronics CD1-5R2
C2: Murata GRM31CR60J106K
C4: Murata GRM32ER71H475K
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Load Current (A)
Figure 1. 1MHz 10V -28V to 5V/3A Step-down Converter
November 8, 2007
Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Conve
SEMTECH [ SEMTECH CORPORATION ]
