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POWER MANAGEMENT

Jan. 13, 2011

1

18V, 3A, 350kHz Step-Down

Switching Regulator

SC4525D

Typical Application Circuit

Features

Input range: 3V to 18V

3A Output Current

350kHz Fixed Switching 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

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Description

The SC4525D is a 350kHz constant frequency peak

current-mode step-down switching regulator capable of

producing 3A output current from an input ranging from

3V to 18V. The SC4525D is suitable for next generation

XDSL modems, high-definition TVs and various point of

load applications.

Peak current-mode PWM control employed in the

SC4525Dachievesfasttransientresponsewithsimpleloop

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 SC4525D is available in SOIC-8 EDP package.

Figure 1. 350kHz 10V -16V to 5V/3A Step-down Converter

Efficiency of the 1MHz 10V-28V to 5V/3A Step-Down Converter (Front Page)

Fig.1b: 350kHz 10-16V to 5V/3A Step-Down Converter (Front Page Efficiency w/12Vin)

Efficiency

40

45

50

55

60

65

70

75

80

85

90

0

0.5

1

1.5

2

2.5

3

Load Current (A)

SC4525A

12

12

SC4525D

GND

IN

SW

BST

L1

10mH

C1

0.33 mF

SS/EN

COMP

FB

D2

20BQ030

8.25k

R6

33.2k

22 nF

C8

47pF

C5

2.2nF

L1 : Coiltronics CD1-100

OUT

5V/3A

D1

1N 4148

10 V–16V

RSET

C2 : Murata GRM31CR60J 476M

C4

10mF

C4 : Murata GRM31CR61E 106K

VIN

C2

47mF

C7

R4

60.4k

R5

11.5k

R7

Fig.1a : 350 kHz10V

- 16 V to5V/3 A Step

-

Down Converter

( Front Page Schematic

)