EV-114

AAT2803 EVAL: Six-Channel White LED

Backlight Charge Pump with Flash

Introduction

The AAT2803 EVAL board demonstrates the functionality of the AAT2803 and its application as a white LED

backlight driver with flash capability. The backlighting section of the AAT2803 uses a low-noise, constant fre-

quency charge pump DC/DC converter with tri-mode load switch (1X), fractional (1.5X) and doubling (2X) con-

version to maximize efficiency and operate over a wide input voltage range. Dedicated to the flash section is a

low-noise, constant frequency doubling (2X) charge pump that is capable of delivering 300mA of pulsed current.

The backlighting section is programmable with the AS

face and is capable of driving up to six independent LED channels. LED constant current levels are set from

a 16-level logarithmic scale and four additional low current settings are available down to 50µA.

This document describes the evaluation board and its accompanying user interface. In addition, a brief Getting

Started section is included to help the user begin operating the evaluation board. A schematic of the complete

circuit is shown in Figure 1, and the actual board layout is given in Figures 2 and 3. For additional information,

please consult the AAT2803 product datasheet.

Schematic

Figure 1: Evaluation Board Schematic.

VDD

1

GP5

2

GP4

3

GP3

4

GP2

5

GP1

6

GP0

7

VSS

8

PIC12F675

U3

1

µF

C1

1

µF

C2

1

µF

C3

1

µF

C4

10

µF

C8

1k

Ω

R1

1k

Ω

R2

1k

Ω

R3

330

Ω

R6

J1

1

2

3

4

5

0

FLASH

SW1

1

2

3

4

5

0

MOVIE

SW2

RED

LED7

1

2

3

4

5

0

LIGHT

SW3

DC+

DC-

MV

LT

FL

D2

D1

D5

D3

AAT9513

U2

D0

20

Ω

R5

1

Ω

R4

1

µF

C5

Flash LED

EN3

GND

1

µF

C6

GND

GND

GND

GND

GND

DC+

GND

GND

JPx

C1-

1

C1+

2

VOUT_FL

3

VIN

4

EN/FL

5

N/C

6

GND

13

VIN

14

GND

15

D1

16

D2

17

D3

18

19 20 21 22 23 24

12 11 10 9

8 7

AAT2803

U1

D6

D4

GND

GND

EV-114.2005.06.1.0

1