AP5725

WHITE LED STEP-UP CONVERTER

AP5725

Document number: DS31844 Rev. 3 - 2

1 of 17

www.diodes.com

July 2010

© Diodes Incorporated

Description

The AP5725 is a step-up DC/DC converter specifically

designed to drive white LEDs with a constant current. The

device can drive 2 ~ 6 LEDs in series from a Li-Ion cell.

Series connection of the LEDs provides identical LED

currents resulting in uniform brightness and eliminates the

need for ballast resistors. For driving higher number of LEDs,

AP5725

also

supports

a

single

feedback

of

parallel

connected multiple strings of equal number of LEDs.

The AP5725 switches at 1.2MHz that allows the use of tiny

external

components.

A

low

0.25V

feedback

voltage

minimizes power loss in the current setting resistor for better

efficiency.

Pin Assignments

1

2

3

74

6

OVP

FB

5

EN

SW

(Top View)

GND

SOT26 / TSOT23-6

SW

OVP

1

2

3

6

5

4

GND

FB

EN

(Top View)

DFN2020C-6

Features

•

High efficiency: 84% typical

•

Fast 1.2MHz switching frequency

•

Current limit and UVLO protections

•

Internal thermal shutdown

•

Internal Over Voltage Protection

•

Integrated soft-start function

•

SOT26, TSOT23-6 and DFN2020C-6: Available in

“Green” Molding Compound (No Br, Sb)

•

Lead Free Finish/ RoHS Compliant (Note 1)

Applications

•

Cellular Phones

•

PDAs, Hand held Computers

•

Digital Cameras

•

MP3 Players

•

GPS Receivers

Notes:

1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at

http://www.diodes.com/products/lead_free.html.

Typical Application Circuit

V

IN

SW

EN

GND

FB

AP5725

C

OUT

1uF

12

L1

22uH

D1

V

IN

1uF

OVP

2~6 LEDs

PWM Dimming

OFF

ON

Figure 1. Typical Application Circuit