Bernard Seront wrote:
>
> Thanks a lot to all who answered my question.
>
> I checked again my LCD (it wouldn't work on 5V and would on 6.2V): it is
> effectively an extended range temperature: it works fine if I give it a
> negative voltage on Vee.
> I still don't understand why it would work on ~6 V with Vee to ground, though.
>
> Now that's annoying as I don't really want to go with a negative supply just
> for that: is there any trick to do the job just with +5V available?
> I tried to ground Vee, and float the LCD ground at about 1 - 1.5 V, but that
> wouldn't work (the LCD -showed- me it didn't like it!).
>
> One option I see is a Maxim dc-dc pump charge, or switched capacitor,
> inverter (MAX1044/ICL7660, MAX828/829 or MAX853) , looking at their data
> sheets it seems that could do the job. Anyone already tried or used similar
> components?
>
> Bernard.
>
> -----
> Bernard Seront, seront@seism1.ess.sunysb.edu (MIME ok)
> http://rock.ess.sunysb.edu:8080/

As well as the unused pic pin and negative charge pump generator, I have also
used a ni-cad 1.2V battery, and the negative rail of a MAX-232 that was needed
in the cct for comms anyway, however these days they (Max-232's) seem to be
getting cheaper.

I guess you could add one just for the low power negative rail required by these
types of displays.

Don McKenzie donmck@labyrinth.net.au
DonTronics Tullamarine, Australia
http://www.labyrinth.net.au/~donmck

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