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I want to control LCD from parallel port but instead of using current from pin 7 i would like to add external power source. I dont like the idea to have variable current that is depending on motherboard. By external power source i mean battery from nokia phone which is 3.7V.
Do i need to use 74LCX245 anyway ?
If not what should i do with pin 7 ?

74LCX245 is there to convert the +5v levels of the parallel port data pins to +3.3v level as the PCD8544 controller isn't meant to take +5v to it's input pins. +3.3v because of the LP2950 3.3v regulator that is used to power the 74LCX245 and the lcd. So using external power source doesn't change anything. But the circuit might work just fine without the 74LCX245 anyway but I'm not promising anything.
If you're using external power source you can just leave the lpt pin 7 not connected. Or you could use it to switch the external power supply.

Does 74LCX245 expects +5v input ? Becouse my external power is 3.6v or 3.7v.
I will use pin7 to switch external power supply as you suggested.

You should power the 74LCX245 from the same powersupply as the lcd itself. 74LCX245 datasheet in the Recommended Operating Conditions says that it's meant for supply voltage of 2.0v to 3.6v.