Sometimes the LCD module gets mounted in a product in such way that it is on the end of a cable going from the MCU board up to where the LCD is mounted. Then if the LCD is subject to possible ESD as induced from the operator or another part of the equipment operational environment there can be an upset problem. With upset the LCD can become unresponsive to the MCU trying to send commands and data to the LCD controller chip. In these cases it may sometimes be necesary for the MCU to be able to turn off the power going to the LCD module by way of a FET or BJT. If the MCU has to "unhang" the LCD module by this technique it would be necessary to send the initialization commands again after the LCD power is turned back on.

Often times ESD problems like this can be solved by appropriate packaging design but if that is not an option then a power scheme like I describe may be just the solution.

Michael Karas