SC4524A Datasheet, PDF (1/18 Pages) Semtech Corporation – 28V 2A Step-Down Switching Regulator

SC4524A
28V 2A Step-Down Switching Regulator
POWER MANAGEMENT
Features
 Wide input range: 3V to 28V
 2A 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 SC4524A is a constant frequency peak current-mode
step-down switching regulator capable of producing 2A
output current from an input ranging from 3V to 28V. The
switching frequency of the SC4524A is programmable
up to 2MHz, allowing the use of small inductors and
ceramic capacitors for miniaturization, and high input/
output conversion ratio. The SC4524A is suitable for
next generation XDSL modems, high-definition TVs and
various point of load applications.
Peak current-mode PWM control employed in the
SC4524A 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 SC4524A is available in SOIC-8 EDP package.
Typical Application Circuit
SS270 REV 4
VIN
10V – 28V
C4
2.2mF
IN
BST
SW
SS/EN SC4524A
COMP
ROSC
FB
GND
C7
10nF
C8
10pF
R7
28.0k
C5
2.2nF
R5
18.2k
D1
1N4148
C1
0.1mF
L1
8.2mH
R4
42.2k
OUT
5V/2A
D2
20BQ030
R6
10.5k
C2
22mF
L1: Coiltronics DR73-8R2
C2: Murata GRM31CR60J226K
C4: Murata GRM31CR71H225K
90
85
80
75
70
65
60
55
50
45
40
0
Efficiency
VIN = 12V
VIN = 24V
0.5
1
1.5
2
Load Current (A)
November 2, 2007
Figure 1. 1MHz 10V-28V to 5V/2A Step-down Converter

Efficiency of the 1MHz 10V-28V to 5V/2A Step-Down C