BUF05704 Datasheet, PDF (13/25 Pages) Burr-Brown (TI) – 18 - V SUPPLY MULTI - CHANNER GAMMA CORRECTION BUFFER

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APPLICATION INFORMATION
The requirements on the number of gamma correction
channels vary greatly from panel to panel. Therefore,
the BUFxx704 series of gamma correction buffers
offers different channel combinations. The BUF11704
offers 10 gamma channels plus one V_COM channel,
whereas the BUF07704 provides six gamma channels
plus one V_COM. The V_COM channel on both models can
be used to drive the V_COM node on the LCD panel.
V_DD
BUF05704, BUF06704
BUF07704, BUF11704
SBOS277E − JUNE 2004 − REVISED DECEMBER 2004
Gamma correction voltages are often generated using
a simple resistor ladder, as shown in Figure 21. The
BUFxx704 buffers the various nodes on the gamma
correction resistor ladder. The low output impedance of
the BUFxx704 forces the external gamma correction
voltage on the respective reference node of the LCD
source driver. Figure 21 shows an example of the
BUFxx704 in a typical block diagram driving an LCD
source driver with 10- or 6-channel gamma correction
reference inputs.
BUFxx704
R_S(1)
(2)
Source Driver
Gamma 1
(1)
(2)
Gamma 2
(1)
(2)
Gamma 3
(1)
(2)
(1)
(2)
(1)
(2)
Gamma (n − 2)
Gamma (n − 1)
Gamma (n)⁽³⁾
V_COM
(1) Optional Increases stability.
(2) Optional capacitor.
(3) n = max number of gamma channels
on respective BUFxx704.
Figure 21. LCD Source Driver Typical Block Diagram
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