HD66710 Datasheet, PDF (43/73 Pages) Hitachi Semiconductor – (Dot Matrix Liquid Crystal Display Controller/Driver)

HD66710
Oscillator Circuit
• Relationship between Oscillation frequency and Liquid Crystal Display Frame Frequency
The liquid crystal display frame frequencies of Figure 21 apply only when the oscillation frequency is
270 kHz (one clock period: 3.7 µs).
1) When an external clock is used 2) When an internal oscillator is used
Clock
OSC1
HD66710
OSC1
Rf
OSC2
HD66710
The oscillator frequency can be
adjusted by oscillator resistance
(Rf). If Rf is increased or power
supply voltage is decreased, the
oscillator frequency decreases.
The recommended oscillator
resistor is as follows.
• Rf = 91 kΩ ± 2% (V_CC = 5V)
• Rf = 75 kΩ ± 2% (V_CC = 3V)
Figure 20 Oscillator Circuit
(1) 1 /17 duty cycle
200 clocks (6-dot font width: 240 clocks)
V_CC
V1
COM1
V4
V5
1 234
1 frame
16 17 1 2 3
1 frame
16 17
Item
Line selection period
Frame frequency
Normal Display Mode (LP = 0)
5-Dot Font Width 6-Dot Font Width
200 clocks
240 clocks
79.4 Hz
66.2 Hz
Low Power Mode (LP = 1)
5-Dot Font Width 6-Dot Font Width
50 clocks
60 clocks
79.4 Hz
66.2 Hz
(2) 1 /33 duty cycle
100 clocks (6-dot font width: 120 clocks)
V_CC
V1
COM1
V4
V5
1 234
1 frame
32 33 1 2 3
1 frame
32 33
Item
Line selection period
Frame frequency
Normal Display Mode (LP = 0)
5-Dot Font Width 6-Dot Font Width
100 clocks
120 clocks
81.8 Hz
68.2 Hz
Low Power Mode (LP = 1)
5-Dot Font Width 6-Dot Font Width
50 clocks
60 clocks
81.8 Hz
68.2 Hz
Figure 21 Frame Frequency
333