FEATURES
• I2C Compatible Programmable DAC to Set the
Output Current
• Ensured Monotonic DAC
• Non-Volatile Memory to Hold the Setting
• EEPROM in System Programmable
• No External Programming Voltage Required
• Maximum Interface Bus Speed is 400 kHz
• SON-10 Package

APPLICATIONS
• TFT Panel Factory Calibration
• Digital Potentiometer
• Programmable Current Sink

DESCRIPTION
The LM8342 is an integrated combination of a non-
volatile register (7 bits EEPROM) and a DAC
controlled current source. Using the LM8342, the
VCOM calibration procedure is simplified by elimination
of the potentiometer adjustment task. This adjustment
task is currently performed at the factory using a
trimmer adjustment tool and visual inspection.
The VCOM adjustment can be done electronically in
production, using the I2C compatible interface. The
factory operator can physically view the screen headon
(frontal viewing) when performing this step, easing
manufacturing especially for large TFT panels.
The VCOM level is typically at half AVDD (determined
by R1 and R2) and is buffered by the actual VCOM
driver. By controlling the level of IOUT, the VCOM level
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 RSET and an analog
reference (AVDD). 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 VCOM adjustment. Controlling the DAC
setting of the LM8342 is done via its I2C 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 I2C compatible interface.