eric in port b if microcontroller, o/p current is 25 ma. lcd backlight is 50ma. how do i drive
Look at the transistor circuit I posted earlier.
470R > BC547 base > lcd backlight to collector> high side of lcd backlight to +5V. [ it may have to be +7V.!, but try +5V first]
For a quick first test of the transistor, dont connect the base resistor to the PIC, just connect it to the +3.3V. The backlight should go on/off as you touch the base resistor to +3.3V and 0V alternately.
Once that test works OK, then think about using the PIC pin to drive the 470R.
OK.?