AMC1351-Q1: Wide input voltage benefit?

Hi Ochi-san,

There are multiple benefits:

The AMC1351's wider input range offers the ability to transfer a higher signal to noise ratio signal across the isolation barrier, assuming the magnitude of the noise present in the system is static. 

Furthermore, for systems that are sensing lower voltages (i.e. ~5V, compared to 1000V) the wider input range allows for higher accuracy measurements without calibration since the resistor divider will contribute less error to the measurement. 

Lastly, for applications that will calibrate for gain error, the wider input voltage range allows for higher accuracy measurements for any voltage magnitude. This is due to the input impedance of the AMC1351 being ~1Mohm compared to ~1Gohm for the AMC1311. This input impedance is in parallel with the sensing resistor and may have up to +/-15% variation; a potential error that is eliminated by gain calibration. 

This Isolated Amplifier Accuracy Excel Calculator can help customers calculate these benefits: https://www.ti.com/lit/zip/sbar013

However, please keep in mind that the tolerance and temperature drift of the resistor divider is not included and this has a large impact on the overall error of the measurement. 

Please let me know if you have additional questions.  

Hi Ochi-san,

After gain and offset calibration, the remaining sources of error are: Gain drift, offset drift, nonlinearity (INL) and nonlinearity drift.