AAT2803 datasheet(13/16 Pages) AAT

13 / 16 page

AAT2803

Six-Channel White LED Backlight

Charge Pump with Flash

2803.2006.12.1.6

AS2Cwire Addressing

Five addresses are available to enable all of the

part's functionality. Two 4-bit registers control the

main and sub-channels, giving 16 settings for each.

The main and sub-channels are programmed to the

same constant current level by using Address 1.

Use Addresses 2 and 3 to program the main and

sub-channels independently. Use Address 4 to pro-

gram the Max Current register, which sets the Max

Current scale. Lastly, Address 5 programs the Low

Current register. The Low Current register controls

the efficient Low Current mode. When the Max

Current register is programmed to 1, 2, or 3, chang-

ing the data for Addresses 1-3 will result in the cor-

responding values found in the Constant Current

Programming Levels table.

When the Max Current register is programmed to 4,

the part is programmed to operate in Low Current

mode and the Data for Addresses 1-3 is irrelevant.

In Low Current mode, the Low Current register

takes precedence. See the Low Current Register

Settings table below for the current level settings

and main/sub-configurations that result.

Max Current and Low Current Registers

Use the Max Current and Low Current registers to

program constant current settings outside of the

20mA Max scale. By default (without changing the

Max Current register), the backlight charge pump

operates in the 20mA Max scale (see Constant

Current Programming Levels). For example, to

change to the 30mA Max scale, address the Max

Current register with 20 rising edges and pause for

TLAT. Program the Max Current register with 2 rising

edges and pause for TLAT. The part will next operate

in the same Data row, but for the setting found in the

30mA Max column. Next, to change to a different

setting on the 30mA Max scale, address the D1-D6

stant current level with 1-16 rising edges. The part

will update to the new Data setting according to the

Constant Current Programming Levels table.

The backlight charge pump has a distinct Low

Current mode with ultra-low quiescent current. For

drive currents of 2mA or less, the part operates with

significantly reduced quiescent current. This is par-

ticularly useful for applications requiring an "always

on" condition such as transmissive displays. As an

example, to change to Low Current mode, address

the Max Current register with 20 rising edges and

pause for TLAT. Program the Max Current register

with 4 rising edges and pause for TLAT. Address the

Low Current register with 21 rising edges and

pause for TLAT. Program the Low Current register

with 1-16 rising edges. The part will update to the

new Low Current mode setting and operate with

significantly reduced quiescent current.

EN/SET

Addressed

Address

Edges

1&2: D1-D6

Current

1: D1-D4 Current

2: D5-D6 Current

3: Max Current

4: Low Current

AS2Cwire Serial Interface Timing

Address

Data

EN/SET

Address

Data Reg 1

Data Reg 2

2 . . .

n <= 16

TLO

TLAT

LAT

AAT2803 Datasheet(PDF) 13 Page - Advanced Analog Technology, Inc.

AAT2803 Datasheet(HTML) 13 Page - Advanced Analog Technology, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL