LC75838W Datasheet, PDF (31/36 Pages) ON Semiconductor – Duty General-Purpose LCD Driver

The INH Pin and Display Control
LC75838W
Since the IC internal data (the display data and the control data) is undefined when power is first applied, applications
should set the INH pin low at the same time as power is applied to turn off the display (This sets the S1 to S38,
S39/COM10, S40/COM9, and COM1 to COM8 to the VLCD4 level and the P1 to P3 to the VSS level.) and during this
period send serial data from the controller. The controller should then set the INH pin high after the data transfer has
completed. This procedure prevents meaningless displays at power on. (See figures 3, 4, and 5.)
Power Supply Sequence
The following sequences must be observed when power is turned on and off. (See figures 3, 4, and 5.)
• Power on: Logic block power supply (VDD) on  LCD driver block power supply (VLCD) on
• Power off: LCD driver block power supply (VLCD) off  Logic block power supply (VDD) off
However, if the logic and LCD driver blocks use a shared power supply, then the power supplies can be turned on and
off at the same time.
• 1/8 duty
t1
VDD
VLCD
t2
t3
INH
CE
Internal data (D1 to D80)
Undefined
Display and control data transfer
VIL
tc
VIL
Defined
Undefined
Internal data (D81 to D160)
Undefined
Defined
Undefined
Internal data (D161 to D240)
Undefined
Defined
Undefined
Internal data (D241 to D320)
PC1 to PC3
Internal data CT0 to CT3, CTC
SC, BU, DT1, DT2
Undefined
Undefined
Defined
Defined
Undefined
Undefined
• t1  0
• t2 > 0
• t3  0 (t2 > t3)
• tc .... 10s min
Figure 3
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