Hi Sir,
Customer wanna use AMC1305M25-Q1.
For voltage measurement of AMC1305M25-Q1,
How to combine the parameters in the case of accuracy calculation?
Can I calculate it?
Thanks for your clarification.
Regards,
Hi Frank,
Since AMC1305M25-Q1 is a modulator, the performance of the measurement is ultimately set by the settings of the sigma delta filter module (SDFM), so accuracy calculations of analog parameters do not necessarily give an accurate representation of performance. I've provided an example from this document below: https://www.ti.com/lit/wp/sbaa359a/sbaa359a.pdf
However, I've provided an example accuracy calculation below where the AMC1305M25-Q1 is sensing 240Vpk through 2x 200kohm and a sensing resistance of 432ohm, also utilizing an R3' resistor of432ohm. For more information on R3' and using a low input impedance device for voltage sensing, please see this document: https://www.ti.com/lit/an/sbaa350a/sbaa350a.pdf
A few questions if you would like me to tailor this calculation to your customers system: What is the peak high voltage, temperature range and resistor divider resistance?
Hi Frank,
I've attached both calculations for the conditions you listed below. The main source of error is due to the low input input impedance of the AMC1305 being in parallel with the sensing resistance as discussed here: https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1023946/faq-does-ti-provide-guidance-on-input-resistance-variation-due-to-manufacturing-process-temperature-drift-and-lifetime-for-isolated-converters
This is not an issue if the customer plans on performing a gain calibration as shown in the error tables below. The customer could also consider moving to a device with higher input impedance such as AMC1336, AMC1311, AMC3330, or AMC1350 to reduce this source of error if gain calibration will not be performed.
