The display uses the PCD8544 controller chip from Philips and were used in Nokia 3310 and 5110 cell phones. This chip is designed to run only at 3.3V and have 3v communication levels, so for 5V microcontrollers a logic level shifter is required (otherwise you could easily damage the display).
If you want to use the backlight, that can draw up to 80mA (4 white LEDs at 20mA each). The backlight pin is connected to a transistor so you can PWM all 4 LEDs at once from a microcontroller pin.This guide was first published on Dec 17, 2012. It was last updated on Sep 20, 2018. This page (Power Requirements) was last updated on May 04, 2015.