On 4/12/2012 4:25 PM, Richard Prosser wrote:
> Basically I was thinking about a system where the output voltage was=20
> limited to, say, 4.5V by means of a series resistor & precision zener=20
> / TL431 etc. This would then be independent of supply voltage but=20
> subject to any temperature drift in the clamping device. The minimum=20
> voltage would be close to zero - if you need it to be 0.5V, then you'd=20
> need to add it in - use an opamp circuit to provide the clamping=20
> function with a 0.5V offset.? RP=20

Gotcha now.  But space is super-tight, so op-amp is probably out.  I can=20
just send the appropriate digital signal range (103 to 922) to get 0.5V=20
to 4.5V, with the only side effect of reducing resolution by 20%.


--=20
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