Basic help with LCDs

Thread Starter


Joined Jan 18, 2015
I am trying to connect a LCD to a PIC MCU.

For power, I am using 4 AA cells with a 7805. Disconnected from the circuit, the DMM shows 5.7 volts from the 7805. When I measure at the LCDs power input, the DMM shows 5.4 volts. The LCD power input is wired directly to the 7805. Should I be concerned about this? Does this mean that the 7805/batteries are unable to supply the required current?

When I measure current going in to the LCD the DMM shows 0.4 maximum. The datasheet for the LCD says that it uses "typically" 2 milliamp. Does this further my hypothesis that the batteries cannot supply the required current?


Joined Oct 2, 2009
Are you using new AA's?
The dropout voltage for a 7805 is 2V, so to get 5.0V at the output, you will need to start with 7V or higher. Look at LDO regulators...