hd66420 Renesas Electronics Corporation., hd66420 Datasheet - Page 39

• Manufacturer Part Number: hd66420
• Description: Ram-provided 160 Channel 4-level Grey Scale Driver For Dot Matrix Graphics Lcd
• Manufacturer: Renesas Electronics Corporation.

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.
Partial display
0.82 * (V
Partial display function uses 1/4 bias ratio from V
with data bit 2 to 0 of R16.
12
11
10
Example.1 LCD bias level
9
8
7
6
5
4
3
2
1
0
0
CC
-GND) V
1/80 duty Display (1/9 bias, VLCD = 12V, GND = 0V)
07
Contrast (R16)
CC
0F
0.997 (V
17
CC
-GND)
(maximum)
1F
VLCD
V1O
V2O
V3O
V4O
V5O
CC
to GND. Eight levels of contrast can be selected
Example.2 LCD bias level
5
4
3
2
1
0
0
Partial Display (1/4 bias, VCC = 5V, GND = 0V)
Contrast (R16)
4
(maximum)
HD66420
7
V
V1O
V2O
V3O
V4O
V5O
CC
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