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SDA
SCL-S
SCL
WP
P
6 2
7
3
9
8
4 5
1
10
OUT
SET
+
-
V
COM
GND
AV
DD
V
DD
AV
DD
R1
R2
I
OUT
CONTROLLER
V
DD
I
2
C INTERFACE
WP
N
15 k:
15 k:15 k:
R
SET
LM8342
LM8342
www.ti.com
SNOSAM0B –NOVEMBER 2005–REVISED MARCH 2013
LM8342 Programmable TFT V
COM
Calibrator with Non-Volatile Memory
Check for Samples: LM8342
1
FEATURES
DESCRIPTION
The LM8342 is an integrated combination of a non-
2
• I
2
C Compatible Programmable DAC to Set the
volatile register (7 bits EEPROM) and a DAC
Output Current
controlled current source. Using the LM8342, the
• Ensured Monotonic DAC
V
COM
calibration procedure is simplified by elimination
• Non-Volatile Memory to Hold the Setting
of the potentiometer adjustment task. This adjustment
task is currently performed at the factory using a
• EEPROM in System Programmable
trimmer adjustment tool and visual inspection.
• No External Programming Voltage Required
The V
COM
adjustment can be done electronically in
• Maximum Interface Bus Speed is 400 kHz
production, using the I
2
C compatible interface. The
• SON-10 Package
factory operator can physically view the screen head-
on (frontal viewing) when performing this step, easing
APPLICATIONS
manufacturing especially for large TFT panels.
• TFT Panel Factory Calibration
The V
COM
level is typically at half AV
DD
(determined
by R1 and R2) and is buffered by the actual V
COM
• Digital Potentiometer
driver. By controlling the level of I
OUT
, the V
COM
level
• Programmable Current Sink
can be tuned. The current level at the output of the
LM8342 is a fraction (1/128 to 128/128) of a
maximum current which is set by R
SET
and an analog
reference (AV
DD
). The actual fraction is determined
by the 7-bit DAC. As a result, the output current of
the LM8342 has a good temperature stability yielding
a very stable V
COM
adjustment. Controlling the DAC
setting of the LM8342 is done via its I
2
C compatible
interface. The actual DAC setting is stored in a
volatile register. Using a “Write to EE” command the
data can be stored permanently in the embedded
EEPROM. At power on of the device, the EEPROM
data is copied to the volatile register, setting the DAC.
At any time, the data in the EEPROM can be
changed again via the I
2
C compatible interface.
Typical Application
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Copyright © 2005–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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