BUF12800 Datasheet, PDF (13/20 Pages) Burr-Brown (TI) – REFERENCE VOLTAGE GENERATOR for LCD GAMMA CORRECTION

www.ti.com
PROGRAMMABLE V_COM
Channels A−F of the BUF12800 can drive more than
100mA up to 2V to the supply rails (see Figure 5, typical
characteristic Output Voltage vs Output Current).
Therefore, any of these channels can be used to drive the
V_COM node on the LCD panel. To store the gamma and the
V_COM values, an external EEPROM is required. During
power-up of the LCD panel, the timing controller can then
read the EEPROM and load the values into the BUF12800
to generate the desired gamma voltages as well as V_COM
voltages. Figure 14 shows channels A and B of the
BUF12800 being used for V_COM voltages.
INDEPENDENTLY PROGRAMMABLE RGB
GAMMA: BUF20800
Some very high resolution LCD screens require the
adjustment of the gamma voltages for each color
(Red—R, Green—G, Blue—B). The BUF20800, available
Q1 ’05, offers 20 programmable gamma channels. By
using 6 channels for each color, 18 channels would be
used in total for adjusting the gamma. In addition to those,
1 or 2 channels could be used to program V_COM.
TOTAL TI PANEL SOLUTION
In addition to the BUF12800 programmable voltage
reference, TI offers a complete set of ICs for the LCD
panel market, including gamma correction buffers,
source and gate drivers, timing controllers, various
power-supply solutions, and audio power solutions.
Figure 15 shows the total IC solution from TI.
BUF12800
SBOS315 − DECEMBER 2004
SDA
SCL
BUF12800
Control Interface
Out A
Out B
V_COM
Out C
Out D
Out K
Gamma
References
Out L
Figure 14. BUF12800 Used for Programmable
V_COM
2.7 V−5 V
TPA3005D2
TPS3008D2
Audio
Speaker
Driver
TPS65140
TPS65100
LCD
Supply
15 V
26 V
−14 V
3.3 V
Reference
Gamma Correction
BUF12800
n
n
Source Driver
Logic and
Timing
Controller
High−Resolution
TFT−LCS Panel
V_COM
Figure 15. TI LCD Solution
13