ISO7221A: Question about the maximum input signal voltage.

Kazuya Nakai59

Guru 21835 points

Part Number: ISO7221A

Tool/software:

Hello guys,

One of my customers has the following question about the maximum input signal voltage of ISO7221A.

Could you please give me your reply?

Q.
ISO7221A datasheet say on page 1 that All inputs are 5V tolerant when supplied from a 2.8V or 3.3V supply and all outputs are 4mA CMOS.
But on page 4, it shows that Vi(Voltage at IN, OUT) is -0.5V(Min)~Vcc+0.5V in 5.1 Absolute Maximum Ratings table.

Which is correct?
Are the device all input 5V tolerant or not?

Your reply would be much appreciated.

Best regards,
Kazuya.

4 months ago

0 Aaditya V. 4 months ago

TI__Mastermind 18745 points

Hello,

Thanks for reaching out.

The input voltage for this device is dependent on the supply voltage of the respective side. For example, if VCC1=5V, then the Vi (max) = 5.5V. If VCC1 = 3.3V, then Vi(max) = 3.8V. Please see the absolute maximum ratings below:

Please note that we recommend keeping the input voltage the same as the respective supply voltage, as per the recommended operating conditions:

Considering the above information, violating the absolute maximum ratings can cause unexpected behavior and/or damage to the device. we do not guarantee the operation of the device past the absolute maximum ratings. For example, if the VCCx=3.3V but the Vi = 5V, the absolute maximum ratings will be violated and can potentially cause the device to have damage. We recommend following the recommended operating conditions when designing the device in your system, while keeping the absolute maximum ratings in mind.

Regards,
Aaditya V

0 Kazuya Nakai59 4 months ago in reply to Aaditya V.

Guru 21835 points

Hello Aaditya,

Thank you very much for your reply.

Could I ask you an additional question?

Q.
Is the description on page1, "All inputs are 5V tolerant when supplied from a 2.8V or 3.3V supply" wrong description?

Your reply would be much appreciated.

Thank you again and best regards,
Kazuya.

0 Aaditya V. 4 months ago in reply to Kazuya Nakai59

TI__Mastermind 18745 points

Hello,

Please allow me to check with my team regarding this.

Regards,
Aaditya Vittal

0 Aaditya V. 3 months ago in reply to Aaditya V.

TI__Mastermind 18745 points

Hello,

Thank you very much for your patience. After talking with our extended team, i was able to get some feedback regarding your request. Very sorry for the delay and time this took.

The ISO7221A device can support input voltages up to 5V when supply is less than 5V, meaning the inputs are overvoltage tolerant inputs. Thank you for pointing out the confusion and we will work to fix this in an upcoming revision of the datasheet.

Additional FAQ for more info: https://e2e.ti.com/support/isolation-group/isolation/f/isolation-forum/1502147/faq-iso6441-what-are-overvoltage-tolerant-inputs-of-digital-isolators/5771541?tisearch=e2e-sitesearch&keymatch=ISO6441%20AND%20FAQ#5771541

Regards,
Aaditya V

0 Kazuya Nakai59 3 months ago in reply to Aaditya V.

Guru 21835 points

Hello Aaditya,

Thank you very much for your reply.

We got it and will wait for the device datasheet update.

Thank you again and best regards,
Kazuya.

0 Kazuya Nakai59 3 months ago in reply to Kazuya Nakai59

Guru 21835 points

Hello Aaditya,

Let me confirm.

Is this information correct?
Is it really okay to tell the customer that the previous information was incorrect and that this device is 5V tolerant?

Could you give me your reply?

Thank you and best regards,
Kazuya.

0 Aaditya V. 3 months ago in reply to Kazuya Nakai59

TI__Mastermind 18745 points

Hi Kazuya,

I understand your concern here and how to proceed in regards to this is a bit difficult. Please allow me some time to check with my team in regards to customer.

Regards,
Aaditya

0 Kazuya Nakai59 3 months ago in reply to Aaditya V.

Guru 21835 points

Hi Aaditya,

Thank you very much for your checking.

I see. I will wait for your next update.

Thank you again and best regards,
Kazuya.

0 Aaditya V. 3 months ago in reply to Kazuya Nakai59

TI__Mastermind 18745 points

Hi Kazuya,

Please give me an additional day to discuss with my team.

Regards,
Aaditya

0 Kazuya Nakai59 3 months ago in reply to Aaditya V.

Guru 21835 points

Hi Aaditya,

Thank you very much for your checking.

Yes. I will wait for your reply.

Thank you again and best regards,
Kazuya.

0 Aaditya V. 3 months ago in reply to Kazuya Nakai59

TI__Mastermind 18745 points

Hi Kazuya,

I have reached out and am still waiting on a reply. I expect to have response tomorrow.

Regards,
Aaditya V

0 Aaditya V. 3 months ago in reply to Aaditya V.

TI__Mastermind 18745 points

Hi Kazuya,

Thanks for your patience and sorry for the delay.

The ISO7221A device can support input voltages up to 5V when supply is less than 5V, meaning the inputs are overvoltage tolerant inputs. This has not been updated in the datasheet to reflect this, but we are able to tell customers in regards to the input.

Regards,
Aaditya V

0 Kazuya Nakai59 3 months ago in reply to Aaditya V.

Guru 21835 points

Hi Additya,

Thank you very much for your strong supports and confirming.

I understood that ISO7221A input has 5V tolerant and hope updating the datasheet.

Thank you again and best regards,
Kazuya.

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ISO7221A: Question about the maximum input signal voltage.