Interfacing LCD display to 3V circuits

Usually, we are used to connecting LCDs to 5V systems. LCD controllers usually require a 5V power supply, and there must be some compliant circuitry used when interfacing to 3V systems like ARM LPC2000 microcontrollers.

Here are few examples how this problem could be solved.

Solution number 1

Standard LCD microcontroller can work with lowered power supply voltage to 2.7V. For this negative voltage for regulating contrast is needed. For this special inverting IC is needed or another solution. In this case, there is the ability to write and read from the LCD controller.

Solution number 2

This solution is simpler. It doesn’t need negative voltage. But in this case, you can only write data to the LCD controller -no ability to read for instance LCD status and so on.

It is recommended to connect resistors (about 1kOm) in each data line.

Solution number 3

Use 8 bit Shift register to send data to LCD.

No ability to read.

Solution number 4

The best choice would be to use a low voltage LCD like WX1602T. This kind of LCD has voltage multipliers on board, and you don’t have to wary about the power supply.

They also have programmable contrast adjusting and programmable temperature compensation as well.

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