BUF11705 Datasheet, PDF (11/17 Pages) Burr-Brown (TI) – 22 - V Supply, 10 + 1 Channel Gamma Correction Buffer

BUF11705
www.ti.com
CAPACITIVE LOAD DRIVE
The BUF11705 has been designed to sink/source large
dc currents. Its output stage has been designed to
deliver output current transients with little disturbance
of the output voltage. However, there are times when
very fast current pulses are required. Therefore, in LCD
source driver buffer applications, it is quite normal for
capacitors to be placed at the outputs of the reference
buffers. These capacitors improve the transient load
regulation and will typically have values of 100pF or
more. The BUF11705 gamma buffers were designed to
drive capacitances in excess of 100 pF. The output is
able to swing within 150 mV of the rails on
10 mA of output current, as shown in Figure 24.
OUTPUT VOLTAGE vs OUTPUT CURRENT
18.0
17.8
Channels 1−5
17.6
V_DD = 18 V
T_A = 25_C
17.4
17.2
17.0
1.0
0.8
0.6
0.4
Channels 6−10
0.2
0
0 5 10 15 20 25 30 35 40 45 50
Output Current − mA
Figure 24. Gamma Buffer Drive Capability
SBOS349 − DECEMBER 2005
APPLICATIONS WITH >10 GAMMA CHANNELS
When a greater number of gamma correction channels
are required, two or more BUF11705 devices can be
used in parallel, as shown in Figure 25. This capability
provides a cost-effective way of creating more refer-
ence voltages over the use of quad-channel op amps or
buffers. The suggested configuration in Figure 25
simplifies layout. The various different channel versions
provide a high degree of flexibility and also minimize
total cost and space.
BUF11705
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
OUT8
OUT9
OUT10
OUT11
OUT12
OUT13
OUT14
OUT15
OUT16
OUT17
OUT18
OUT19
OUT20
BUF11705
GMA1
2
3
4
5
6
7
8
9
GMA10
GMA11
12
13
14
15
16
17
18
19
GMA20
Figure 25. Creating > 10 Gamma Voltage
Channels
11