HD66727 Datasheet, PDF (25/97 Pages) Hitachi Semiconductor – Low-Power Dot-Matrix Liquid Crystal Display Controller/Driver with Key Scan Function

HD66727
LED Output Port
The HD66727 includes three LED/back-light driving output ports and three general output ports. These
ports can control the LED from the microcomputer through the serial interface.
Booster (DC-DC Converter)
The booster doubles or triples a voltage input to the Vci pin. With this function, both the internal logic units
and LCD drivers can be controlled with a single power supply.
Oscillator (OSC)
The HD66727 can provide R-C oscillation simply by adding an external oscillation-resistor between the
OSC1 and OSC2 pins. The appropriate oscillation frequency for operating voltage, display size, and frame
frequency can be obtained by adjusting the external-resistor value. Clock pulses can also be supplied
externally. Since R-C oscillation is halted during the standby mode, current consumption can be reduced.
V-Pin Voltage Followers
A voltage follower for each voltage level (V1 to V5) reduces current consumption by the LCD drive power
supply circuit. No external resistors are required because of the internal bleeder-resistor, which generates
different levels of LCD drive voltage. The voltage followers can be turned off while multiplexing drive is
not being used.
Contrast Adjuster
The contrast adjuster can adjust LCD contrast by varying LCD drive voltage by software. This function is
suitable for selecting appropriate brightness of the LCD or for temperature compensation.
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