ST7628
7.4 Gary-Scale Display
ST7628 incorporates a 4FRC & 31 PWM function circuit to display a 64 gray-scale display.
7.5 Oscillation circuit
ST7628 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 96-bits 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 7.5.
Figure 7.5 2-frame AC Driving Waveform (Duty Ratio: 1/70)
Ver 1.4
42/213
2008/08
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
