SC4524B_08 Datasheet, PDF (1/18 Pages) Semtech Corporation – 18V 2A Step-Down Switching Regulator

SC4524B
18V 2A Step-Down Switching Regulator
POWER MANAGEMENT
Features
 Wide input range: 3V to 18V
 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 SC4524B is a constant frequency peak current-mode
step-down switching regulator capable of producing 2A
output current from an input ranging from 3V to 18V. The
switching frequency of the SC4524B is programmable
up to 2MHz, allowing the use of small inductors and
ceramic capacitors for miniaturization, and high input/
output conversion ratio. The SC4524B is suitable for
next generation XDSL modems, high-definition TVs and
various point of load applications.
Peak current-mode PWM control employed in the
SC4524B 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 SC4524B is available in SOIC-8 EDP package.
Typical Application Circuit
SS270 REV 4
VIN
10V – 16V
C4
2.2mF
IN
BST
SW
SS/EN SC4524B
COMP
ROSC
FB
GND
C7
10nF
C8
10pF
R7
30.1k
C5
1nF
R5
18.2k
D1
1N4148
C1
0.1mF
L1
6.8mH
R4
102k
OUT
5V/2A
D2
20BQ030
R6
25.5k
C2
22mF
L1: Wurth 744 778 9006
C2: Murata GRM31CR60J226K
C4: Murata GRM31CR61E225K
90
85
80
75
70
65
60
55
50
45
40
0
Efficiency
VIN = 12V
0.5
1
1.5
2
Load Current (A)
Figure 1. 1MHz 10V-16V to 5V/2A Step-down Converter
June 2, 2008