icl7107 scale factor

"maxi"

** Ambiguous question.

Do you really want 1 volt to read 1.999 ??

** See page 10 under the heading 'Reference Voltage".

** Just make Vref equal to 500 mV. 1 volt input will then read 1.999 or overflow.

....... Phil

I had a quick look at the intersil datasheet, it seems that you alter the Voltage Reference. See p10 in the data sheet

martin

You mean you want it to read 1999 at 1 volt in? If so, then just use a

500mV reference rather than a 1V reference with the 2V circuit. You can cut the integration capacitor value in half to get a bit better performance (by increasing the swing at the integrator output), but you probably won't notice the difference.

If you just want to use it with a 3-digit display, and read 999 at 1V in then just use the 2V circuit and wire the output drive for the segments B,C (double current of the other outputs) to an overrange LED.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Probably i dont't explicate me well.

i have a signal that rise from 0 to 600 mV at max.

I should use the 2v full scale for haven't overflow.

But i've only 3 digit precision.So i'd like to mesure from 0 to 600mv with all 3 1/2 digit precision.

Example: with 2 volt full scale at 300mV the dyspaly show 0.300 and so on.I'd like that dyspaly show 300.0.

Probably is not possible

Full-scale on a 3-1/2 digit A/D is 0.999 volts, with 100% overrange, it's 1.999 volts. You should look into using a 4-1/2 digit A/D such as the ICL7135. Full scale on a 4-1/2 digit A/D is 0.9999 volts, so your 300mv input would read as .3000. Moving the decimal point would give you the 300.0 display.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Some days you\'re the dog, some days the hydrant.

Not possible. You could make it read 300. (not 300.0).

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

"maxi"

** A "3.5 digit" meter has a maximum of 2000 counts.

That is you lot - as the poms would say.

....... Phil