HD404818 Datasheet, PDF (68/100 Pages) Hitachi Semiconductor – 16-digit LCD driver

HD404818 Series
Large LCD Panel Driving and Driving Voltage (V_LCD): When using a large LCD panel, lower the
dividing resistance by attaching external resistors in parallel with the internal dividing resistors (figure 37).
Since the liquid crystal display board is of a matrix configuration, the path of the charge/discharge current
through the load capacitors is very complicated. Moreover, since it varies depending on display conditions,
the value of resistance cannot be determined by simply referring to the load capacitance of the liquid crystal
display. The value of resistance must be experimentally determined according to the demand for power
consumption of the equipment in which the liquid crystal display is implemented. Capacitor C (0.1 to 0.3
µF) is recommended to be attached. In general, R is 1 kΩ to 10 kΩ.
Figure 37 shows a connection when changing the liquid crystal driving voltage (V_LCD). In this case, the
power supply switch for the dividing resistors (power switch) must be turned off. (Bit 1 of the LCR register
is 0.)
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