HD66760 Datasheet, PDF (74/105 Pages) Hitachi Semiconductor – 104 X 80-dot Graphics LCD Controller/Driver for 256 Colors

HD66760
When an Internal Booster and Internal Operational Amplifiers are Used
To supply LCD drive voltage using the internal VLCD regulator and step-up circuit, an internal booster and
internal operational amplifiers should be connected as shown in figure 50. Keep the power-supply voltage
(VLPS) of the operational amplifier higher than the output voltage (V1REF) of the VLCD regulator. Contrast
can be adjusted through the CT bits of the contrast control instruction.
The HD66760 incorporates a voltage-follower operational amplifier for each of V1 to V5 to reduce current
flowing through the internal bleeder-resistors, which generate different liquid-crystal drive voltages. Thus,
potential difference between V_LPS and V1 must be 0.1 V or higher, and that between V4 and GND must be 1.4
V or higher. Note that the OPOFF pin must be grounded when using the operational amplifiers. Place a
capacitor of about 1 µF (B characteristics) between each internal operational amplifier (V1OUT to V5OUT
outputs) and GND and stabilize the output level of the operational amplifier. Adjust the capacitance value of
the stabilized capacitor after the LCD panel has been mounted and the screen quality has been confirmed.