Ian KD8CEC has been looking at power consumption on the Nextion display and how to effectively dim the screen for portable µBITx work, where you want low current drain.
The following picture show’s Ian’s display (2.8″ TJC Chinese version) at Full Power:
And the screen fed with a series 50 ohm resistor (1/2 watt rated or more):
The slightly dimmer display halves the current consumption from 89mA to 44mA with a series 50 ohm resistor (made up of two 100 ohm resistors in parallel (or 3 x 150 ohm resistors in parallel). The Nextion screen has a built in software dimming function, and this can be adjusted in Ian’s Nextion display firmware. However, the feature generates noise in the µBITx and is not recommended.
Resistor installation
Installing a series resistor (with a value between 20 ohms and 100 ohms) in the +5V power lead will cause the display to be dimmed, but function normally (except for use of the micro-SD card reader). The resistor could be installed across a slide switch or toggle switch (with one pole shorted and the other going through the resistor) to allow for two settings (normal, dimmed). This could be handy for night time or portable use. The circuit diagram for this is as below:
For further details see Ian’s website.