ADD8702_15 Datasheet, PDF (1/8 Pages) Analog Devices – 12-Channel Gamma Buffers with V Buffer

12-Channel Gamma Buffers
with V_COM Buffer
ADD8702
FEATURES
Programmable 12-Channel Gamma Reference Generator
Mask Programmable Adjustable V_COM Buffer
Upper/Lower Outputs Swing to V_DD/GND
Continuous Output Current: 10 mA
V_COM Peak Output Current: 250 mA
Outputs with Fast Settling Time for Load Change
Output Pins Are Compatible with ADD8701
Single-Supply Operation: 7 V to 16 V
Supply Current: 15 mA Max
APPLICATIONS
TFT LCD Panels
GENERAL DESCRIPTION
The ADD8702 is a low cost, mask programmable, 12-channel
gamma reference generator, plus an adjustable V_COM driver. This
part is designed to provide gamma correction for high resolution
TFT LCD panels. The 12 gamma reference levels and V_COM are
mask programmable to 0.3% resolution using the on-chip 500
chain resistor string. This reduces component and board costs.
The ADD8702 provides a complete programmed set of gamma
voltage references for the LCD source drivers. These references
settle quickly to load change. The V_COM output is stable with
high capacitive loads and can source or sink 250 mA peak cur-
rent. The V_COM output level can be adjusted using an external
trim-potentiometer or discrete resistors.
FUNCTIONAL BLOCK DIAGRAM
VDD 1
VCOM ADJ 2
VHIGH 3
VIN11 4
VIN10 5
VIN9 6
V_IN8 7
V_IN7 8
32 31 30 26 28 27 26 25
9 10 11 12 13 14 15 16
24 GND
23 VDD
22 VGMA6
21 VGMA5
20 VGMA4
19 VGMA3
18 VGMA2
17 VGMA1
The output pins are compatible with the ADD8701. This allows
for single board design and fast turns for prototyping using the
initial ADD8701 board design.
The ADD8702 is specified over the temperature range of –40°C
to +85°C and comes in the 32-lead lead frame chip scale pack-
age (LFCSP) for compact board space.
PANEL
TIMING
CONTROLLER
TIMING AND CONTROL
SCAN DRIVER CONTROL
GAMMA
REFERENCE
VOLTAGES
SOURCE DRIVER
NO. 1
384
SCAN
DRIVERS
768
RGB
SOURCE DRIVER
NO. 2
384
TFT COLOR PANEL
1024 ؋ 768
SOURCE DRIVER
NO. 8
384
Figure 1. Typical SVGA TFT LCD Application
ADD8702
GAMMA
V_COM
REV. 0
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