HD66712 Datasheet, PDF (53/88 Pages) Hitachi Semiconductor – Dot-Matrix Liquid Crystal Display Controller/Driver

HD66712U
Oscillator Circuit
1) When an external clock is used 2) When an internal oscillator is used
Clock
OSC1
HD66712
OSC1
Rf
OSC2
HD66712
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.
i) HD66712S
• Rf = 91 kΩ ± 2% (V_CC = 5V)
• Rf = 75 kΩ ± 2% (V_CC = 3V)
ii) HD66712U
• Rf = 130 kΩ ± 2% (V_CC = 5V)
• Rf = 110 kΩ ± 2% (V_CC = 3V)
Figure 22 Oscillator Circuit
(1) 1 /17 duty cycle
1-line selection period
V_CC
V1
COM1
V4
V5
1 234
1 frame
16 17 1 2 3
16 17
1 frame
Normal Display Mode (LP = 0)
Low Power Mode (LP = 1)
Item
5-Dot Font Width 6-Dot Font Width 5-Dot Font Width 6-Dot Font Width
Line selection period 200 clocks
240 clocks
60 clocks
72 clocks
Frame frequency
79.4 Hz
66.2 Hz
66.2 Hz
55.1 Hz
Note: At the calculation example above for displayed frame frequency, all oscillator frequencies are
270 kHz (1 clock = 3.7 µs).
(2) 1 /33 duty cycle
1-line selection period
V_CC
V1
COM1
V4
V5
1 234
1 frame
32 33 1 2 3
32 33
1 frame
Normal Display Mode (LP = 0)
Low Power Mode (LP = 1)
Item
5-Dot Font Width 6-Dot Font Width 5-Dot Font Width 6-Dot Font Width
Line selection period 100 clocks
120 clocks
60 clocks
72 clocks
Frame frequency
81.8 Hz
68.2 Hz
68.2 Hz
56.8 Hz
Note: At the calculation example above for displayed frame frequency, all oscillator frequencies are
270 kHz (1 clock = 3.7 µs).
Figure 23 Frame Frequency
416