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I am looking for a graphical display that I can control using TTL-level signals (e.g. an Arduino MEGA2560). I have found this display from Mouser: https://nl.mouser.com/datasheet/2/291/NHD_320240WG_BxTFH_VZ-2953010.pdf but there is something I don't quite understand.

In the datasheet it refers to Vee being typically 23.6V. This voltage strikes me as strange, as this means I need to provide two supply voltages, of which one is much higher than what I "normally" encounter.

Is this normal for a display like this? Or do (larger) displays exist that run on 5V entirely?

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It would appear this one does run on 5 V alone, or at least it generates the -25 V rail internally. Page 4 of the datasheet you link refers to \$V_{EE}\$ as a "negative voltage output" [emphasis mine], and the schematic on the same page shows it being used just as a reference for a potentiometer used to set contrast. It shows Vdd, Vss, LED-A, and LED-K connected to power supplies, but Vee is not connected to any supply.

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enter image description here

To my mind, that suggests that \$V_{EE}\$ is an output, not an input, to be used for biasing the contrast potentiometer. Applying voltage from an external supply may actually damage it.

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  • \$\begingroup\$ It even says on page 1 (I see that now), VZ stands for "built-in negative voltage". \$\endgroup\$
    – Bart Friederichs
    Commented Mar 11, 2023 at 13:35

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