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Hi friends..... plz help me.... i am working on a small project using 89S52,Keypad,lcd,MOSFET IRF9540N, and 7805 IC. 7.4 v Lipo battery. my concept is to turn on and off LCD with the keypress from keypad. Am using 7805 to step down voltage to 5v and then 5v is being supplied to 89s52 and MOSFET source pin. Mosfet drain pin is attached to LCD and gate pin to port 3^5. lcdis straight away grounded. Lcd is attached to port 1. my code and circuit works well.... but the problem is the battery gets drained in 10-12 hours even if lcd is in off state. At initial stage have kept my lcd off... and when button 1 is presses from keypad the lcd goes on and again if keypad is pressed its goes off.. so for that i have put port3^5 pin which is connected to MOSFET gate...low at initial stage to keep the lcd off... and port3^5 high when button 1 is pressed.... i have also low all the signal pins port1 which is connected to lcd.... but even then my battery gets drained.... dont know what is it that is conauming my power....
so, if micro disables all clocks it goes to MegaWatt, better have a fire extinguisher ready