ISO7041: IEC60079-11:2023 cl 7.10.2 Differential leakage current

Stefan Brehm

Part Number: ISO7041

Tool/software:

Hi,

because of the new Edition of the IEC60079-11:2023 there are new requirements to signal isolator which are not optical see cl. 7.10.2 (text below).

If no parameter is noted in the datasheet a test can be done. see cl. 9.9. (see text below)

However, I don't want to do the test.

Are there information in the datasheet which show that parameter or is possible to calculate it with a datasheet parameter as shown below?

I use a 115.2kbit Baud rate = appr. 115.2kHz with a supply current of 3.3V max.3.4V.

Is it possible to use from the ISO7041 (rev. D) datasheet the Cio parameter (Barrier capacitance, input to output) with 1.5pF in chapter 7.6 to calculate
the needed differential leakage current?

Calculation example:
U=3.4V (Umax)
C=Cio = 1.5pF
f= 115.2kHz

Xc = 1/(2 x Pi x f x C) = 921.035kOhm
I=U/Xc = 3.4/921.035kOhm = 3.7µA

I need this information for anactual approval.

Thanks

Best regards
Stefan

1 month ago

+1 Aaditya V. 1 month ago

TI__Genius 12245 points

Hi Stefan,

Thanks for reaching out and welcome to E2E!

I have answered your questions below:

Stefan Brehm said:
Are there information in the datasheet which show that parameter or is possible to calculate it with a datasheet parameter as shown below?

I believe the process which you have explained in your post is correct. The equation X[CIO] = 1 / 2*π*f*CIO and I = U/X[CIO] can be used to find the maximum leakage current like you have shown already. I believe your calculations are correct as it reflects the capacitive reactance equation. This equation is not directly given on the datasheet since it is not a typical question or request we receive from customers.

Stefan Brehm said:
Is it possible to use from the ISO7041 (rev. D) datasheet the Cio parameter (Barrier capacitance, input to output) with 1.5pF in chapter 7.6 to calculate
the needed differential leakage current?

Yes, the CIO barrier capacitance value can be used to do the leakage current calculation.

A similar request may be a helpful E2E post for you well as a second reference: https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/1344472/iso1042-q1-leakage-current-value/5133052?tisearch=e2e-sitesearch&keymatch=koteshwar%2520AND%2520CIO#5133052

Regards,
Aaditya Vittal

0 Stefan Brehm 1 month ago in reply to Aaditya V.

Prodigy 10 points

Hi Aaditya,

thanks for your response.

That seems good that you have the same opinion as me. I will use this calculation for my approval for my device which uses the ISO7041.

Thanks a lot for the quick and detailed support.

Best regards

Stefan

Isolation

Isolation forum

ISO7041: IEC60079-11:2023 cl 7.10.2 Differential leakage current