Go Down

Topic: Negative Contrast Voltage to Run LCD at 3.3V (Read 1 time) previous topic - next topic

mdenzien


I'd like to experiment with running various 5V LCD displays at 3.3V. From what I can gather, many 5V units will actually work if you provide a negative contrast voltage, say -1V, at pin 3. Is there an easy way to produce this negative voltage in a typical Arduino or Arduino clone circuit? Could this be done by adding a small battery to the circuit with the battery's positive terminal attached to the ground of the main circuit, and a contrast pot across the small battery to provide an adjustable negative voltage?

Thank you.

floresta

Quote
Could this be done by adding a small battery to the circuit with the battery's positive terminal attached to the ground of the main circuit, and a contrast pot across the small battery to provide an adjustable negative voltage?

Yes, this technique will work.  You have to do this for some 5v LCD modules as well, usually extended temperature varieties.

Don

jluciani

It is also not difficult do create a 5V supply with a switched-capacitor
converter. See the schematic in my LCD interface datasheet --

http://wiblocks.luciani.org/ZB1/ZB1-LCD-CHAR-index.html

(* jcl *)
www: http://www.wiblocks.com
twitter: http://twitter.com/wiblocks

Go Up