hd66421 Renesas Electronics Corporation., hd66421 Datasheet - Page 28

• Manufacturer Part Number: hd66421
• Description: Ram-provided 160 Channel 4-level Grey Scale Driver For Dot Matrix Graphics Lcd
• Manufacturer: Renesas Electronics Corporation.

Partial Display Function
The HD66421 can display only a part of a full
display. The duty ratio of this partial display is 1/8
and rest of display is scanned with unselected
levels. The position of this partial display can be
located at any position with using partial display
position register. To launch this mode, following
processes are needed:
(1) supplied voltage to VLCD must be cut off,
PWR bit can be used if external voltage supplier is
controlled with DCON output (R0)
(2) set DTY bits (R1)
(3) set display position (R11)
(4) set contrast level (R16)
Preliminary
Start line R5
Y address
R5+7
H'00
H'63
ABCD
H'00
H'01
H'02
H'03
H'04
H'05
H'06
H'07
H'08
H'09
H'0A
H'0B
R11
Display
RAM
COM1
COM9
COM17
COM25
COM33
COM41
COM100
COM92
COM84
COM76
COM68
COM60
Figure 24 Partial Display
Table 6 Partial Display Block
ADC= 0
R11=H'04
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
COM8
COM16
COM24
COM32
COM40
COM48
COM93
COM85
COM77
COM69
COM61
COM53
28
LCD Panel
ABCD
The clock frequency may be 220kHz at normal
display mode. When a partial display is driven,
oscillation frequency will be 18kHz, 1/12.5 of that
of normal display mode. This function is useful for
lower
frequency, follow the process which is showed in
Figure 28.
Warning:
VLCD must be cut off when partial display
mode is launched. Vcc is supplied to LCD
driving circuit instead of VLCD. So if VLCD
is supplied externally during partial display
mode, Vcc short-circuit to VLCD.
COM8
COM16
COM24
COM32
COM40
COM48
COM93
COM85
COM77
COM69
COM61
COM53
power
ADC= 1
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
–>
dissipation.
COM1
COM9
COM17
COM25
COM33
COM41
COM100
COM92
COM84
COM76
COM68
COM60
COM33
COM40
COM100
COM49,COM50 (Not used)
COM1
COM51,COM52 (Not used)
Rev. 1.1E '99.02.10
To
change
HD66421
clock