ACPL-C87X optical isolation

rberna

Joined Feb 27, 2017
2
You should not connect Vout- to GND since it is biased at VOCM (1.23V). Simply keep Vout- unconnected, and use Vout+. Remember that Vout+ is at the same offset 1.23V. Not using Vout- means you should have half the expected gain, 0.5 V/V

Vout+ = 1.23 --> Vin = 0
Vout+= 2.23 --> Vin = 2

Of course not using the differential outputs, the accuracy will be worse since there is not guarantee that VOCM will stay at 1.23V. A certain improvement could be obtained if you measure both Vout+ and Vout- through two ADC of the microcontroller and calculate the difference by firmware: at least the VOCM wandering is canceled.

These considerations are just from analysis of the datasheet, use them at your risk

Regards.
 

Thread Starter

karas

Joined Sep 8, 2011
211
You should not connect Vout- to GND since it is biased at VOCM (1.23V). Simply keep Vout- unconnected, and use Vout+. Remember that Vout+ is at the same offset 1.23V. Not using Vout- means you should have half the expected gain, 0.5 V/V

Vout+ = 1.23 --> Vin = 0
Vout+= 2.23 --> Vin = 2

Of course not using the differential outputs, the accuracy will be worse since there is not guarantee that VOCM will stay at 1.23V. A certain improvement could be obtained if you measure both Vout+ and Vout- through two ADC of the microcontroller and calculate the difference by firmware: at least the VOCM wandering is canceled.

These considerations are just from analysis of the datasheet, use them at your risk

Regards.
Thanks so much
 
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