MAX1512 Maxim Integrated Products, MAX1512 Datasheet - Page 11

• Manufacturer Part Number: MAX1512
• Description: EEPROM-Programmable TFT VCOM Calibrator
• Manufacturer: Maxim Integrated Products

The VCOM adjustment and the EEPROM programming
must be performed with an external programming cir-
cuit. Refer to the MAX1512 evaluation kit for a complete
programming circuit solution.
Use a circuit similar to the conceptual diagram shown
in Figure 8 to drive CTL. The accuracy of the program-
ming voltage (V
retention. The use of a comparator is recommended to
verify the correct programming voltage has been
reached. A complete design example of a CTL pro-
gramming circuit is presented in the MAX1512 evalua-
tion kit data sheet.
The CTL pin is exposed at the LCD panel connector and
is subject to electrostatic discharge (ESD). Often an RC
filter is used to improve an input’s resilience to ESD. If a
filter is added between the LCD panel connector and
CTL, ensure that the RC time constant is short enough to
avoid interfering with CTL pulses or the EEPROM pro-
gramming timing. An RC time constant less than 200µs
does not interfere with EEPROM programming.
Figure 8. Conceptual Programming Circuit
EEPROM-Programmable TFT VCOM Calibrator
Applications Information
PP
INTERFACE
Electrostatic Discharge (CTL)
USER
______________________________________________________________________________________
) is critical for proper MAX1512 data
µC
V
PP
VERIFY
0 TO 2.5V
DAC
REF
The CTL pin is internally biased to V
sitive to leakage currents above 0.1µA. When CTL is
not driven, avoid leakage currents around the CTL pin.
Otherwise, reinforce the V
nal resistive voltage-divider.
Use the following guidelines for good layout:
•
•
•
Refer to the MAX1512 evaluation kit for an example of
proper board layout.
Place the VCOM buffer and the R1/R2 voltage-
divider close to the OUT pin (Figure 1). Keep the
VCOM buffer and the R1/R2 voltage-divider close
to each other.
Place R
In noisy environments, bypass capacitors may be
desired on V
capacitors close to the IC with short connections to
the pins.
0 TO 15.5V
SET
close to SET.
DD
and/or V
DD
Leakage Current (CTL)
CTL
/ 2 set point with an exter-
AVDD
Layout Information
MAX1512
. Keep any bypass
DD
/ 2, but it is sen-
11