V

COM

OUT1

OUT2

OUT3

OUT4

V

S

(3)

GND

A

(2)

V

SD

SDA

NC

OUT8

OUT7

OUT6

GND

A

(2)

V

S

(3)

OUT5

GND

D

(2)

BKSEL

A0

BUF08821

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

10

V

COM

V

S

(1)

(1)

(1)

Timing

Controller

3.3V

100nF

1 F

m

(1)

100nF

10 F

m

Source

Driver

Source

Driver

(1)

(1)

(1)

(1)

(1)

V

S

Source

Driver

SCL

APPLICATION INFORMATION

At power-on, the BUF08821 first updates all channels

to midscale (code 1000000000) and then reads the

GENERAL

data for both memory banks into the two sets of

The BUF08821 programmable voltage reference

storage

registers.

This

read

process

requires

allows

fast

and

easy

adjustment

of

eight

approximately 560

μs. After this read is complete, the

programmable gamma reference outputs and one

BUF08821 updates the DACs simultaneously with

data for the bank selected by the BKSEL pin.

The BUF08821 can be powered using an analog

supply voltage from 9V to 20V, and a digital supply

stored in the on-chip, nonvolatile memory. To allow

from 2V to 5.5V. The digital supply must be applied

for programming errors or liquid crystal display (LCD)

before the analog supply to avoid excessive current

panel rework, the BUF08821 supports up to 16 write

and power consumption, or possibly even damage to

operations to each word in the on-chip memory. The

the device if left connected only to the analog supply

BUF08821 has two separate memory banks, allowing

for extended periods of time. Figure 10 shows a

simultaneous storage of two different gamma curves

typical configuration of the BUF08821.

to facilitate dynamic switching between gamma

curves. The BUF08821 also has two storage registers

for each digital-to-analog converter (DAC) channel to

allow fast switching (less than 10

μs) between gamma

curves.

(1) RC combination optional; see the Output Pins ESD Protection Current-Steering Diodes section.

Figure 10. Typical Application Configuration

Copyright © 2008–2009, Texas Instruments Incorporated

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