Hi there,
I'm creating a system to measure temperatures. It's based on the CN0271 except the ADC. I've chosen a faster one. I'm wondering why the negative input of the AD8476 is tied to +2.5 V. Is this done to be able to measure negative temperatures? Like an offset to 2.5V ?
Thanks a lot
Hi Daniel,
AD7990's differential input voltage range condition is +/-REFIN/GAIN. In CN-0271 REFIN(+) = +2.5v, REFIN(-) = GND. Meaning the differential input of the ADC is within +/-2.5V.
The transfer function of the differential amplifier is:
Since Rf/Rg = 1, then,
Moving on, for the AD8495 the full scale output voltage of the device when in single supply mode is 0.025V to 4.9V.
So the Vout,dm of the differential amplifier -2.475V to 2.4V, which suits the conditions of the differential input of ADC.
Let me know if you have any clarifications.
Regards,
Goz
Hi Daniel,
AD7990's differential input voltage range condition is +/-REFIN/GAIN. In CN-0271 REFIN(+) = +2.5v, REFIN(-) = GND. Meaning the differential input of the ADC is within +/-2.5V.
The transfer function of the differential amplifier is:
Since Rf/Rg = 1, then,
Moving on, for the AD8495 the full scale output voltage of the device when in single supply mode is 0.025V to 4.9V.
So the Vout,dm of the differential amplifier -2.475V to 2.4V, which suits the conditions of the differential input of ADC.
Let me know if you have any clarifications.
Regards,
Goz
