Why negative voltage on old character LCDs?

Post Reply
Megacircuits
Posts: 18
Joined: Wed Sep 12, 2018 6:17 pm

Why negative voltage on old character LCDs?

Post by Megacircuits » Thu Jun 27, 2019 8:37 pm

Why did the old character LCDs have a negative voltage?

focus
Site Admin
Posts: 31
Joined: Mon Jan 22, 2018 1:58 pm

Re: Why negative voltage on old character LCDs?

Post by focus » Sun Jul 21, 2019 1:25 am

Older character, segment and monochrome graphic displays required a negative voltage to deal with temperature swings. More power is required to drive a monochrome display as the temperature drops.

Newer character displays have a built in circuit with a charge pump (bump circuit) the increases the output voltage necessary to keep the display active.

Post Reply