HD66420 Datasheet, PDF (39/52 Pages) Hitachi Semiconductor – (RAM-Provided 160 Channel 4-Level Grey Scale Driver for Dot Matrix Graphics LCD)

HD66420
Example.1 LCD bias level
1/80 duty Display (1/9 bias, VLCD = 12V, GND = 0V)
12
VLCD
11
V1O
10
V2O
9
8
7
6
5
V3O
4
3
V4O
2
V5O
1
0
0
07
0F
17
1F
Contrast (R16)
(maximum)
Example.2 LCD bias level
Partial Display (1/4 bias, VCC = 5V, GND = 0V)
5
V_CC
V1O
4
V2O
V3O
3
V4O
2
V5O
1
0
0
4
7
Contrast (R16)
(maximum)
• Partial display
0.82 * (V_CC-GND) ≤ V_CC ≤ 0.997 (V_CC-GND)
Partial display function uses 1/4 bias ratio from V_CC to GND. Eight levels of contrast can be selected
with data bit 2 to 0 of R16.
LCD drive levels bias ratio: LCD driving levels bias ratio can be selected from 1/6, 1/7, 1/8 or 1/9.
Power Supply: The HD66420 needs the external power supply for LCD driving circuit. If this power
circuit has on/off control, the HD66420 controls the external power supply circuit by setting PWR bit.
External Power Supply Circuit: When the internal operational amplifier cannot fully drive the LCD panel
used, V1O to V5O voltages can be supplied from external power supply circuit. Here, the AMP bit must be
set to 1 to turn off the internal power supply circuit.
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