add8754dacpz-reel7 Analog Devices, Inc., add8754dacpz-reel7 Datasheet - Page 24

• Manufacturer Part Number: add8754dacpz-reel7
• Description: Lcd Panel Power, Vcom, And Gate Modulation
• Manufacturer: Analog Devices, Inc.

The V
steps in the panel manufacturing process. In a typical panel
production environment, such a process can take additional
time to complete and, therefore, impacts production throughput.
One additional concern is that a potentiometer typically used
only for calibration offers limited resolution. The resistance can
drift over time and can be noticeable after a few years of operation.
The production throughput, image quality, and panel reliability
concerns can all be solved by using a digital potentiometer. As
shown in Figure 27, AD5259, a low cost 256-step digital poten-
tiometer with nonvolatile memory, can calibrate the ADD8754
V
In the worst case, where the temperature, aging effect, and
resistance tolerance of the AD5259 are all accounted for, the
circuit in Figure 27 makes the V
3.0 V to 5.0 V with 15 mV per step adjustment. A micro-
COM
voltage precisely, reliably, and time efficiently.
COM
calibration for flicker reduction is one of the essential
ADJUSTABLE FROM 3V TO 5V WITH
15mV PER STEP ADJUSTMENT
VCOM
4.0V
COM
voltage adjustable from
2.2pF
C10
6kΩ
R
B
Figure 27. ADD8754 with Programmable V
R
1kΩ
A
10kΩ
ADD8754
R3
V
14V
OUT
R4
315kΩ
Rev. 0 | Page 24 of 28
AD5259BRMZ10
A
W
B
GND AD0 AD1
VLOGIC
VDD
SDA
SCL
controller or I
control signal for the AD5259, but ADI provides programming
software that simplifies the calibration process. The software
can be installed in the factory computer, and two tester probes
can be connected to the computer’s parallel port to implement the
V
The V
where:
D is the decimal code of the AD5259 programmable resistance
between the W-to-B terminals.
R
AB
COM
0.1μF
is the AD5259 nominal resistance.
V
C9
programming.
COM
COM
voltage can be calculated as
2.2kΩ
=
COM
R10
256
2
R
C programmer can be used to provide the
D
4
2.2kΩ
+
×
R11
R
R
AB
AB
+
+
SIGNAL FROM FACTORY PC,
SOFTWARE PROVIDED BY ADI
R
R
3
3
×
7
×
V
OUT
ADD8754