LC75844M
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13
INH
and Display Control
Since the IC internal data (D1 to D88, control data) is undefined immediately after applying power, hold INH
low at
same time as applying power to turn off the display (S1/P1 to S4/P4, S5 to S22, COM1 to COM4 V
SS
level), and
serial transfer data from the microprocessor during the period that INH
is low.
When the data transfer is complete, set INH
high.
This procedure will avoid displaying meaningless patterns at startup. (See Figure 3)
Power Sequence
Be sure to observe the following sequence for power ON/OFF (See Figure 3)
Power ON: Logic block power (V
DD
) ON → LCD driver power (V
LCD
) ON
Power OFF: LCD driver power (V
LCD
) OFF → Logic block power (V
DD
) OFF
When the logic block power (V
DD
) and LCD driver power (V
LCD
) are common, both power supplies can be turned
ON/OFF simultaneously.
Note on Controller-used Display Data Transfer
Since the LC75844M is such that display data (D1 to D88) is transferred in 4 times, it is recommended to transfer
display data within 30 [ms] in terms of display quality.
V
DD
V
LCD
t2
t1
t3
tc
Indefinite
Decision
Note: t10
t20
t30 (t2t3)
tc 10s min
V
IL
V
IL
CE
D1 to D44
P0 to P2
DR, SC, BU
Internal data
Internal data (D45 to D88)
Indefinite
Figure 3
INH
Indefinite
Decision Indefinite
Display data, control data transfer
