BUF20820 Datasheet, PDF (16/32 Pages) Burr-Brown (TI) – 18-Channel GAMMA VOLTAGE GENERATOR with Two Programmable VCOM Channels

BUF20820
SBOS330C − DECEMBER 2005 − REVISED OCTOBER 2006
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 BUF20820 can
significantly reduce the time required for gamma voltage
optimization. The final gamma values can be written into
the internal OTP memory to replace a traditional gamma
buffer solution. Figure 13a shows the traditional resistor
string; Figure 13b shows the more efficient alternative
method using the BUF20820.
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The BUF20820 uses the most advanced high-voltage
CMOS process available today, which allows it to be
competitive with traditional gamma buffers.
Programmability offers the following advantages:
D It shortens development time significantly.
D It eliminates manufacturing variance between panels.
D It allows a single panel to be built for multiple
customers, with loading of customer-dependent
gamma curves during final production. This
significantly lowers inventory cost and risk and
simplifies inventory management.
D It allows demonstration of various gamma curves to
LCD monitor makers by simply uploading a different
set of gamma values.
D It provides a simple means of adjusting gamma curves
during final production improve picture quality and
accommodate changes in the panel manufacturing
process or end-customer requirements.
D It decreases cost and space.
a) Traditional
BUFxx704
b) BUF20820 Solution
PC
SDA
SCL
Timing
Controller
BUF20820
V_{COM OUT1}
V_{COM OUT2}
V_COM
OUT1
OUT2
OUT17
Gamma
References
OUT18
SDA
SCL
LCD Panel Electronics
Control Interface
Figure 13. Replacement of the Traditional Gamma Buffer
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