Is power sequencing important?
You must turn on the Vcc supply voltage, then within 10-20 milliseconds apply all of the data signals including the data bits, sync signals and clocks. If you apply the data signals before you apply power, you get into a latch-up condition. The LCD looks like a CMOS device that can draw high current if a signal is before Vcc is turned on. This makes the potential of a high current path to ground from the signal lines if Vcc is not applied before the data signals.
Secondly, the display needs an AC signal to function properly. If only a DC signal is applied, damage can occur. Generally the damage occurs slowly and is a function of duration, temperature and other conditions, but the effect is cumulative and failures will eventually occur. You can also have a latch-up problem if you wait too long to apply the Sync signals.
Some displays have a built-in voltage doubler. If you don't apply the clocks quickly enough, you can create another latch-up condition in the display. A power sequencing latch-up problem almost always shows up as an all white or all black display. Then, if you turn it off and back on it may start working. Latch-up conditions are almost always recoverable. The only time when permanent damage occurs is when excessive power flows through driver’s ESD diodes.
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Tianjin Right Display Co., Ltd.
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ADD:D2 Factory Building, No.7, East of Guwang Road, Jingbin Industrial Park, wuqing district, Tianjin
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TEL : 022-25255909 / 18133876017
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