SC4525C Datasheet, PDF (1/21 Pages) Semtech Corporation – 28V 3A Step-Down Switching Regulator Thermal Shutdown

SC4525C
28V 3A Step-Down Switching Regulator
POWER MANAGEMENT
Features
 Wide input range: 3V to 28V
 3A Output Current
 200kHz to 2MHz Programmable Frequency
 Precision 1V 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
Description
The SC4525C is a constant frequency peak current-mode
step-down switching regulator capable of producing 3A
output current from an input ranging from 3V to 28V. The
switching frequency of the SC4525C is programmable
up to 2MHz, allowing the use of small inductors and
ceramic capacitors for miniaturization, and high input/
output conversion ratio. The SC4525C is suitable for
next generation XDSL modems, high-definition TVs and
various point of load applications.
Peak current-mode PWM control employed in the
SC4525C 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 SC4525C is available in SOIC-8 EDP package.
Typical Application Circuit
SC4525A
V _IN
10V– 28V
C4
4.7mF
IN
BST
SW
SS/EN SC4525C
COMP
FB
ROSC GND
C7
22nF
C8
22pF
R7
12.7k
C5
2.2nF
R5
15.8k
D1
1N4148
C1
0.33mF
L1
5.2mH
R4
33.2k
OUT
5V/3A
D2
20BQ030
R6
8.25k
C2
10mFX3
L1: Coiltronics CD1- 5R2
C2: Murata GRM31CR60J106K
C4: Murata GRM32ER71H475K
Efficiency
90
80
VIN = 12V
VIN = 24V
70
60
50
40
0.0 0.5 1.0 1.5 2.0 2.5 3.0
Load Current (A)
Jan. 13, 2011
Figure 1. 1MHz 10V -28V to 5V/3A Step-down Converter

Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Conve