HD66765 Datasheet, PDF (65/71 Pages) Hitachi Semiconductor – 396-channel Segment Driver with Internal RAM for 4096-color Displays

HD66765
Frame-Frequency Adjustment Function
The HD66765 has an on-chip frame-frequency adjustment function. The frame frequency can be adjusted
by the instruction setting (DIV, RTN) during the LCD drive as the oscillation frequency is always same.
When the display duty is changed, the frame frequency can be adjusted to be the same.
If the oscillation frequency is set to high, an animation or a static image can be displayed in suitable ways
by changing the frame frequency. When a static image is displayed, the frame frequency can be set low
and the low-power consumption mode can be entered. When high-speed screen switching, for an
animated display, etc. is required, the frame frequency can be set high.
Relationship between LCD Drive Duty and Frame Frequency
tion ^{The relationship between the LCD drive duty and the frame frequency is calculated by the following}
expression. The frame frequency can be adjusted in the retrace-line period bit (RTN) and in the operation
a _{clock division bit (DIV) by the instruction.}
cific _{(Formula for the frame frequency)}
Spe _fosc
ary ^{Frame frequency =}
[Hz]
in Clock cycles per raster-row × division ratio × 1/duty cycle
elim^{fosc: R-C oscillation frequency}
Pr ^{Duty: drive duty (NL bit)}
Division ratio: DIV bit
Clock cycles per raster-row: (RTN + 25) clock cycles
65