hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 65

• Manufacturer Part Number: hd66765
• Description: 396-channel Segment Driver With Internal Ram For 4096-color Displays - Hitachi Semiconductor
• Manufacturer: Renesas Electronics Corporation.

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
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
clock division bit (DIV) by the instruction.
(Formula for the frame frequency)
Frame frequency =
Clock cycles per raster-row division ratio 1/duty cycle
fosc: R-C oscillation frequency
Duty: drive duty (NL bit)
Division ratio: DIV bit
Clock cycles per raster-row: (RTN + 25) clock cycles
fosc
65
[Hz]
HD66765