EL7516

FN7333 Rev 6.00

Page 3 of 12

October 9, 2007

Block Diagram

Typical Application Circuit

COMPARATOR

OSCILLATOR

SHUTDOWN

AND START-UP

CONTROL

LX

VDD

FSEL

SHDN

SS

REFERENCE

GENERATOR

PWM LOGIC

CONTROLLER

FET

DRIVER

CURRENT

SENSE

GM

AMPLIFIER

GND

FB

COMP

Pin Descriptions

PIN NUMBER

PIN NAME

DESCRIPTION

1

COMP

Compensation pin. Output of the internal error amplifier. Capacitor and resistor from COMP pin to ground.

2

FB

3

SHDN

Shutdown control pin. Pull SHDN low to turn off the device.

4

GND

Analog and power ground.

5

LX

Power switch pin. Connected to the drain of the internal power MOSFET.

6

VDD

Analog power supply input pin.

7

FSEL

Frequency select pin. When FSEL is set low, switching frequency is set to 620kHz. When connected to

8

SS

Soft-start control pin. Connect a capacitor to control the converter start-up.

1

2

3

4

8

7

6

5

COMP

FB

SHDN

GND

SS

FSEL

VDD

LX

+

+

3.9k



4.7nF

27nF

22µF

0.1µF

10µH

22µF

12V

2.7V TO 5.5V

85.2k



10k



S1