HD66740 Datasheet, PDF (42/95 Pages) Hitachi Semiconductor – 112 x 80-dot Graphics LCD Controller/Driver

HD66740
Oscillation Circuit
The HD66740 can either be supplied with operating pulses externally (external clock mode) or oscillate
using an internal R-C oscillator with an external oscillator-resistor (external resistor oscillation mode).
Note that in R-C oscillation, the oscillation frequency is changed according to the internal capacitance
value, the external resistance value, or operating power-supply voltage. Insert the dumping registance
of about 1.5kΩ to prevent malfunctions caused by over-shoot or under-shoot noise in the external clock
mode.
1) External clock mode
1.5 kΩ
Clock
OSC1
(80 kHz)
HD66740
Insert the dumping resistance.
2) External resistor oscillation mode
The oscillator frequency can be
OSC1
Rf
adjusted by oscillator resistor
(Rf). If Rf is increased or power
OSC2
supply voltage is decreased, the
HD66740
oscillation frequency decreases.
For the relationship between Rf
resistor value and oscillation
frequency, see the Electric
Characteristics Notes section.
Figure 19 Oscillation Circuits
Table 17 Relationship between Drive Duty Ratio and Frame Frequency (fosc = 75 kHz)
Display mode
1-line 2-line 3-line 4-line 5-line 6-line 7-line 8-line 9-line 10-line
Dis- Dis- Dis- Dis- Dis- Dis- Dis- Dis- Dis- Dis-
play play play play play play play play play play
Set value for NL3–0
LCD Drive 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001
Multiplexing 1/8
duty ratio
1/16 1/24 1/32 1/40 1/48 1/56 1/64 1/72 1/80
Drive bias
1/4 1/5 1/6 1/6 1/7 1/8 1/8 1/9 1/9.5 1/10
(recommend-
ed value)
Frame
frequency
73 Hz 73 Hz 73 Hz 73 Hz 72 Hz 74 Hz 74 Hz 73 Hz 65 Hz 59 Hz
One-frame
frequency
1,024 1,024 1,032 1,024 1,040 1,008 1,008 1,024 1,152 1,280
Note: If the frame frequency is low and the display flickers, increase the oscillation frequency (fosc).
Particularly in the 9-line display and 10-line display modes, note that the frame frequency is
lowered.
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