Block Diagram

Pin Assignment

Pin Description

Pin No.

Pin Name

Description

1

SW

Switching pin. Internal power MOSFET drain. Connected to inductor and diode.

2

GND

Signal Ground.

3FB

Feedback pin. Reference voltage. The HT7939 feedback voltage is 200mV. Connect the

sense resistor from FB to GND to set the LED current. Calculate resistor value according to

R

mV

I

FB

LED

=

200

.

4EN

Shutdown & Dimming control input. Don

¢t allow this pin to float.

5

OVP

Over voltage protection pin which is connected to the output.

6

VIN

Input supply pin. The input supply pin for the IC. Connect VIN to a supply voltage between

2.6V~5.5V.

HT7939

Rev 1.10

2

November 3, 2009

S W

G N D

T o p V i e w

V I N

E N

F B

1

2

3

4

6

5

O V P

S O T 2 3 - 6

32V