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Question about working with graphical LCD driver chip

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hm_fa_da

hm_fa_da

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Hello,

i found a graphical LCD driver chip, NT7538 i.e. ( other LCD controllers have same mode too)
in the datasheet, about "standby mode" is written:

"Standby Mode
Stops the operation of the duty LCD displays system and turns on only the static drive system to reduce current consumption to the minimum level required for static drive. The ON operation of the static drive system indicates that the NT7538 is in standby mode. The internal status in the
standby mode is as follows:
(1) Stops the LCD power supply circuit.
(2) Stops the LCD drive and outputs the VSS level as the segment / common driver output.
However, the static drive system still operates.
(3) Holds the display data and operation mode provided before the start of the standby mode.
(4) The MPU can access the built-in display data RAM."

it says turns on "static drive", what does it mean ?!!!
does it mean in this mode, LCD shows the last data on pixels ?!
it says in standby mode all segment and common drivers output VSS level. i just thought because of capacitive nature of LCD segments, it may holds the last display frame !

in fact i want to find the lowest possible power consumption on the LCD for showing a frame. so want to know what happens in standby mode ...
 

The display data will be saved but the LCD will not operate and hence the content of the display will not be visible. However, it will be visible once the system exits the standby mode.

I presume that the standby mode is a feature of the LCD controller chip: this is a power conservation feature. The chip itself will stay powered so that it can exit from the standby mode but some parts may be disabled.
 

but there is another mode named sleep mode !
"Sleep Mode
This mode stops every operation of the LCD display system, and can reduce current consumption
nearly to a static current value if no access is made from the microprocessor. The internal status
in the sleep mode is as follows:
(1) Stops the oscillator circuit and LCD power supply circuit.
(2) Stops the LCD driver and outputs the VSS level as the segment/common driver output.
(3) Holds the display data and operation mode provided before the start of the sleep mode.
(4) The MPU can access the built-in display data RAM.

difference between "sleep" and "standby" mode is static indicator ! static indicator is on in standby mode and is off in sleep mode.
i am just confused about what static indicator means ! :-|
 

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