18-Channel Gamma Buffer
with Regulator
ADD8708
FEATURES
FUNCTIONAL BLOCK DIAGRAM
MASK-PROGRAMMABLE
REGULATOR RESISTORS
18 precision gamma reference outputs
Mask-programmable gamma resistors:
0.2% resolution and 0.1% accuracy
Mask-programmable voltage regulator: 0.4% accuracy
Upper 9 buffers swing to VDD
FB
V
V
V
REG OUT DD DD
700Ω*
GND
GAMMA
BUFFERS
Lower 9 buffers swing to GND
+
–
Single-supply operation: 7.5 V to 16.5 V
Gamma current drive: 15 mA per channel
Peak output current: 150 mA
Output voltage stable under load conditions
Pin-to-pin compatible with ADD8709
48-lead, Pb-free LQFP and LFCSP
1.2V
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
700Ω*
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
18
17
16
15
14
13
12
11
10
9
V
V
V
V
V
V
V
18
17
16
15
14
13
12
11
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
IN
IN
IN
IN
APPLICATIONS
LCD TV panels
LCD monitor panels
GENERAL DESCRIPTION
The ADD8708 is an 18-channel integrated gamma reference for
use in high resolution LCD TV and monitors panels. The out-
put buffers feature high current drive and low offset voltage to
provide an accurate and stable gamma curve. The top nine
channels swing to VDD; the lower nine channels swing to GND.
V
V
IN
10
9
IN
V
V
V
V
V
V
V
V
V
IN
Integrating the gamma setup resistors drastically reduces the
external component count while increasing the gamma curve
accuracy. To accommodate multiple column drivers and panel
architectures, the ADD8708 is mask programmable to a 0.2%
resolution using the on-chip 500 resistor string. An on-board
voltage regulator provides a fixed input for the resistor string,
isolating the gamma curve from the supply ripple.
8
8
7
6
5
4
3
2
1
IN
IN
IN
IN
IN
IN
IN
IN
7
6
5
4
The ADD8708 is specified over the temperature range of
–40°C to +105°C and comes in both a 48-lead, Pb-free,
lead-frame chip-scale package and a Pb-free, low-profile,
quad flat package.
3
2
1
MASK-PROGRAMMABLE
RESISTOR STRING
GND GND
*ESD PROTECTION RESISTORS
Figure 1. 48-Lead LQFP or LFCSP
Rev. 0
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However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
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