ST7689 datasheet(49/195 Pages) SITRONIX

49 / 195 page

ST7689

Version 1.0

Page 49 of 195

2009/10

7.4. Gray-Scale Display

ST7689 incorporates a 4FRC & 31 PWM function circuit to display a 64 gray-scale display.

7.5. Oscillation Circuit

ST7689 is built-in an oscillator circuit. It provides internal clock without external resistor. This oscillator signal is used in

the voltage converter and display timing generation circuit.

7.6. Display Timing Generator Circuit

This circuit generates some signals to be used for displaying LCD. The display clock, which is generated by oscillation

clock, generates the clock for the line counter and the signal for the display data latch. The line address of on-chip RAM is

generated in synchronization with the display clock and the display data latch circuit latches the display data in

synchronization with the display clock. The display data, which is read to the LCD driver, is completely independent of the

access to the display data RAM from the microprocessor. The display clock generates an LCD AC signal (M), which

enables the LCD driver to make an AC drive waveform, and also generates an internal common timing signal and start

signal to the common driver. The frame signal or the line signal changes the M by setting internal instruction. Driving

waveform and internal timing signal are shown in Figure 8.

FR(Internal)

M(Internal)

COM0

COM10

SEGn

Fosc

158

8 9

10 11

159

158

3 4

Figure 8 2 frame AC Driving Waveform (Duty Ratio: 1/160)

ST7689 Datasheet(PDF) 49 Page - Sitronix Technology Co., Ltd.