POWER MANAGEMENT

June 26, 2008



28V 2A Step-Down Switching Regulator

SC4524A

Typical Application Circuit

Features

Wide input range: 3V to 28V

2A 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

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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.

Figure 1. 1MHz 10V-28V to 5V/2A Step-down Converter

Efficiency

40

45

50

55

60

65

70

75

80

85

90

0

0.5

1

1.5

2

Load Current (A)

SS270 REV 4

Fig.1 Efficiency of the 1MHz 10V-28V to 5V/2A Step-Down Converter (Front Page)

SC4524A

GND

IN

SW

BST

L1

8.2mH

C1

0.1mF

SS/EN

COMP

FB

D2

20BQ030

10.5k

R6

42.2k

10nF

C8

10pF

C5

2.2nF

L1: Coiltronics DR73-8R2

OUT

5V/2A

D1

1N4148

10V – 28V

ROSC

C2: Murata GRM31CR60J226K

C4

2.2mF

C4: Murata GRM31CR71H225K

VIN

C2

22mF

C7

R4

18.2k

R5

28.0k

R7

Fig.1 1MHz 10V-28V to 5V/2A Step-Down Converter (Front Page Schematic)