BUF08630_14 Datasheet, PDF (22/35 Pages) Texas Instruments – Programmable Gamma-Voltage Generator and High Slew Rate VCOM

BUF08630
SBOS515A – OCTOBER 2010 – REVISED AUGUST 2012
Table 10 shows the theoretical gain values of the
inverting configuration using the internal resistors,
±15%.
Table 10. Gain Equation
GAIN
G=1
G=2
G=3
G=4
G=5
G=6
RATIO
–R₂/R₁
–R₂/R₁
–R₂/R₁
–R₂/R₁
–R₂/R₁
–R₂/R₁
TYPICAL VALUE
–1.00021
–1.9989
–2.99727
–3.99779
–4.99418
–5.9959
A buffer configuration is achieved using switch
position 8 as indicated in Figure 27
An external user-selectable gain configuration is
achieved using switch position 1, as indicated in
Figure 28. By using a single external gain resistor
value and the internal values of the resistor string, a
wide range of selectable gains can be achieved using
the internal switch configuration.
Table 11 shows the possible gains that can be
achieved with a single 1-kΩ external resistor for each
of the internal switch selections.
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V_COM
Figure 27. Configuration for Switch Position 8
R₁ ext
Feedback
R
V_COM
V_COM
Figure 28. Configuration for Switch Position 1
Table 11. Possible Gains Using a 1-kΩ External Resistor
EXTERNAL RESISTANCE
R₁ ext = 1000 Ω
R₁ ext + R_INT = 2858.75 Ω
R₁ ext + R_INT = 3169.375 Ω
R₁ ext + R_INT = 3601.875 Ω
R₁ ext + R_INT = 4253.125 Ω
R₁ ext + R_INT = 5336.125 Ω
R₁ ext + R_INT = 7501.125 Ω
INTERNAL RESISTANCE
R = 13003.63 Ω
R = 11144.88 Ω
R = 10834.25 Ω
R = 10401.75 Ω
R = 9750.5 Ω
R = 8667.5 Ω
R = 6502.5 Ω
GAIN
–13.0036
–3.89851
–3.41842
–2.88787
–2.29255
–1.62431
–0.86687
SWITCH POSITION
1
2
3
4
5
6
7
22
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