© 2000 SEMTECH CORP.

652 MITCHELL ROAD NEWBURY PARK CA 91320

400mA SmartLDO

TM

SC1534

PRELIMINARY - July 26, 2000

2

APPLICATION CIRCUIT

NOTE:

(1) External switch (Q1): use a low threshold P-channel MOSFET such as Fairchild FDN338P or International

Rectifier IRF7604, or equivalent. (PMOS, typical gate threshold voltage ~ 1V, R

3.3V OUT

3.3VAUX

5V

5V

3.3VAUX

3.3V OUT

C3

0.1uF

C4

10uF

C2

4.7uF

C5

0.1uF

Q1

C1

0.1uF

U1

SC1534CM

1

2

3

4

5

VIN

VAUX GND

VO

DR

TAB

U1

SC1534CS

1

2

3

4

5

6

7

8

VAUX

VIN

VO

DR

GND

GND

GND

GND

C2

4.7uF

Q1

C4

10uF

C1

0.1uF

C3

0.1uF

C5

0.1uF

PIN DESCRIPTION

Pin Name

SO-8 Pin #

TO-263-5L Pin #

Pin Function

DR

4

5

Driver output for external P-channel MOSFET pass element.

GND

5,6,7,8

3/TAB

Logic and power ground.

VAUX

1

1

This is the auxiliary input supply, nominally 3.3V.

VIN

2

2

This is the main input supply for the IC, nominally 5V.

VO

3

4

LDO 3.3V output.