BUF12800 Datasheet, PDF (12/20 Pages) Burr-Brown (TI) – REFERENCE VOLTAGE GENERATOR for LCD GAMMA CORRECTION

BUF12800
SBOS315 − DECEMBER 2004
REPLACEMENT OF TRADITIONAL GAMMA
BUFFER
Traditional gamma buffers rely on a resistor string (often
using expensive 0.1% resistors) to set the gamma
voltages. During development, the optimization of these
gamma voltages can be time consuming. Programming
these gamma voltages with the BUF12800 can
significantly reduce the time required for gamma voltage
optimization. The final gamma values can be written into
an external EEPROM to replace a traditional gamma
buffer solution. During power-up of the LCD panel, the
timing controller can read the EEPROM and load the
values into the BUF12800 to generate the desired gamma
voltages. Figure 13a shows the traditional resistor string;
Figure 13b shows the more efficient alternative method
using the BUF12800.
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BUF12800 uses the most advanced high-voltage CMOS
process available today, which allows it to be competitive
with traditional gamma buffers.
This technique offers significant advantages:
• It shortens development time significantly.
• It allows demonstration of various gamma curves
to LCD monitor makers by simply uploading a
different set of gamma values.
• It allows simple adjustment of gamma curves
during production to accomodate changes in the
panel manufacturing process.
• It decreases cost and space.
a) Traditional
BUFxx704
b) BUF12800 Solution
PC
SDA
SCL
Timing
Controller
EEPROM
BUF12800
Out A
Out B
Out K
Out L
SDA
SCL
LCD Panel Electronics
Control Interface
Figure 13. Replacement of Traditional Gamma Buffer
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