POWER MANAGEMENT



18V, 3A, 350kHz Step-Down

Switching Regulator

SC4525F

© 203 Semtech Corporation

Typical Application Circuit

Features

Input Voltage Range: 3V to 8V

3A Output Current

350kHz Fixed Switching 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

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 SC4525F 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 8V. The SC4525F is suitable for next generation

XDSL modems, high-definition TVs and various point of

load applications.

Peak current-mode PWM control employed in the

SC4525F 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 SC4525F 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)

S C4525A

SC4525F

GND

IN

SW

BST

L1

10mH

C1

0.33mF

SS/EN

COMP

FB

D2

20BQ030

8.25k

R6

33.2k

22nF

C8

47pF

C5

2.2nF

L1: Coiltronics CD 1- 100

OUT

5V/3A

D1

1N4148

10V – 16V

RSET

C2: Murata GRM 31CR60J476M

C4

10mF

C4: Murata GRM 31CR61E106K

V IN

C2

47mF

C7

R4

60.4k

R5

11.5k

R7

Revision 2.