TLV7011-2-3-41EVM: for RCD build

Hi Qianli,

Could you clarify what you mean by error or accuracy? I can't comment on the error or accuracy of the system as a whole as my group wasn't responsible for this reference design.

In terms of the TLV7011, it seems like it's used as a low-side current sensing application with its input fed from a fixed gain current sense amplifier. In this case, the deviations from the ideal would be caused by the input offset voltage and the input bias current of the TLV7011. You could model the errors as typical values of the input offset voltage source on the non-inverting input and typical bias current sources on both inputs. In this case, the offset voltage is in the mV range and the bias currents are in the pA range, so I'd think that the error contributions from those nonidealities would be fairly small.

you know leakage current for RCD is 6mA, 30mA etc. so small I just want to know about the measured current error or accuracy of measurement chain which is in the Design guide TIDA-010237 as RCD measurement solution you have offered. do you have any calculation on this ?

Hi Qianli,

Here is some mention on the error in this design:

3.1.11 MCU Selection, AC and DC Fault Detection

I'm going to transfer this to the group that made the made the ref design, they'll be able to offer better insight into this.

Best, 

Michael 

Hi Qianli,
The subject mater expert is returning to office next week; we can provide a response by 28-August.

thanks, Michael. looking forward to your insight

Hello Qianli,

In Section 3.4 over a range of -10mA to 10mA fault current across -40C to 120C the maximum offset drift measurement error was +/-.8mA. 

thanks for the info. I am just a little concerned about this error for such small current measurement. I would appreciate it if you can share the document with detailed calculation for measurement error.

Can you view this document. The error was measured for the whole system as it was tested across temperature. 

yes...I did. look nice... well, so you don't have any calculation at concept design phase or before PCB build. if you have, please kindly share with me. if don't, thank you for your strong support

I am reaching out to one of the engineers who developed the design to see if they have additional documentation. I will get back by Friday.