3

FN9239.2

April 10, 2007

Block Diagram

Pin Descriptions

PWM LOGIC

CONTROLLER

GM

AMPLIFIER

10 - 186mV

PWM

COMPARATOR

VIN

EN

LX

GND

FB

RSET

L

VIN (2.4V to 5.5V)

2 to 6 LEDs

CIN

ISL97632

SERIAL

INTERFACE

BANDGAP

REFERENCE

GENERATOR

SDIN

FBSW

EN

FET

DRIVER

GM AMP

COMPENSATION

CURRENT

SENSE

1.4MHZ OSCILLATOR AND RAMP

GENERATOR

PIN

NUMBER

PIN

NAME

DESCRIPTION

1

GND

Ground Pin. Connect to local ground.

2

VIN

Input Supply Pin. Connect to the input supply voltage, the inductor and the input supply decoupling

capacitor.

3

EN

Enable Pin. Connect to enable signal to turn-on or off the device. Active High.

4

SDIN

Single-Wire XSD Digital Interface.

5

FB

Feedback Pin. Connect to the cathode of bottom LED and the sense resistor.

6

FBSW

Optional FB Disconnect Switch.

7

VOUT

Output Pin. Connect to the anode of the top LED and the output filter capacitor.

8

LX

Switching Pin. Connect to inductor.

ISL97632