AD74413R I/OP_x maximum input voltage in Voltage Input Mode

Hi rafaelsf ,

SENSEH_x and SENSEL_x pins are for feedback sensing for AO modes, I don't think any adjustment is needed there.

SENSEHF_x and SENSELF_x pins are ADC inputs pins. By adding Resistor divider on the pins, you can scale the voltage however there may be impact on the accuracy of the measurements as AD74413R was not characterized in such scenario. In such case also Current input measurements will be impacted and scaled down, this will result in loosing ADC resolution from system perspective (only part of the input range of the ADC will be utilized in current measurements setting. Note that resistance measurements will be also impacted.) 

Regards,

Arnost 

Hi APavlik,

Yes, I know that the accuracy of the voltage measurements will decrease, as I am increasing the ADC range, reducing the measurement resolution (from 152.59 µV/bit to 366.21 µV/bit).

I could adjust the ADC value in the firmware, my question is about the operation of the AD74413R. I understand that all voltage related measurements will be affected, but is it possible to make that change or the AD74413R will have an internal problem with that new external circuit (adding a resistor to SENSEHF_x and SENSELF_x)?

Thank you very much.

Hi rafaelsf ,

I would suggest adjusting only SENSEHF and SENSELF as outlined previously. 

Internally SENSEHF and SENSELF are high impedance ADC inputs. It is possible to make such change. 

In addition note, that it may be challenging to match ADC inputs attenuation for differential current measurement. This may impact your expected current measurement accuracy also, once SENSELF and SENSEHF pins will have different attenuation of the signal. 

Regards,

Arnost

Hi APavlik,

Ok, thank you very much for your help. I understand the drawbacks due to the resistive divider. Current measurement is not my main goal, so it's ok if I lose some accuracy.

Thank you very much.