HD66765 Datasheet, PDF (64/71 Pages) Hitachi Semiconductor – 396-channel Segment Driver with Internal RAM for 4096-color Displays

HD66765
Oscillation Circuit
The HD66765 can oscillate between the OSC1 and OSC2 pins using an internal R-C oscillator with an
external oscillation resistor. Note that in R-C oscillation, the oscillation frequency is changed according
to the external resistance value, wiring length, or operating power-supply voltage. If Rf is increased or
power supply voltage is decrease, the oscillation frequency decreases. For the relationship between Rf
resistor value and oscillation frequency, see the Electric Characteristics Notes section.
1) External Clock Mode
n Clock
(200 KHz)
tio ^Damping
OSC1
resistance (2 k ) _OSC2
a _HD66765
ific ^{2) External Resistance Oscillation Mode}
pec OSC1
S Rf
Note: The Rf resistance must be located near
the OSC1/OSC2 pin on the chip.
OSC2
ry HD66765
ina^{Figure 48 Oscillation Circuits}
lim ^{When using the HD66765 with the HD66764 common driver, the relationship between the SEG and}
COM output levels is as shown in the following figure. The LCD drive level (VSH, VSL) which is used
e ^{by the HD66765 is supplied from the HD66764 common driver. While the display is off, SEG and COM}
Pr ^{outputs go to GND level.}
M
VCH
COM waveform
VSH
VM
VSL (GND)
No lit
Lit Lit
Lit SEG waveform
No lit No lit
VCL
Figure 49 Relationship with SEG/COM Output Level
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