HD44780 Hitachi Semiconductor (acquired by Renesas), HD44780 Datasheet - Page 38

• Manufacturer Part Number: HD44780
• Description: Dot Matrix Liquid Crystal Display Controller/driver
• Manufacturer: Hitachi Semiconductor (acquired by Renesas)

HD44780U
Relationship between Oscillation Frequency and Liquid Crystal Display Frame
Frequency
The liquid crystal display frame frequencies of Figure 22 apply only when the oscillation frequency is 270
kHz (one clock pulse of 3.7 s).
38
1/8 duty cycle
COM1
1/11 duty cycle
COM1
1/16 duty cycle
COM1
V
V1
V2 (V3)
V4
V5
1 frame = 3.7 s
Frame frequency =
V
V1
V2 (V3)
V4
V5
1 frame = 3.7 s
Frame frequency =
V
V1
V2
V3
V4
V5
1 frame = 3.7 s
Frame frequency =
CC
CC
CC
1
1
1
400
400
200
11.9 ms
11.9 ms
16.3 ms
1
1
1
2
8 = 11850 s = 11.9 ms
2
11 = 16300 s = 16.3 ms
2
16 = 11850 s = 11.9 ms
Figure 22 Frame Frequency
400 clocks
400 clocks
200 clocks
= 84.3 Hz
= 84.3 Hz
= 61.4 Hz
3
3
3
1 frame
1 frame
1 frame
4
4
4
16
11
8
1
1
1
2
2
2