Inquiry regarding internal isolation distance on ISO7631FM

Atsushi Okui

Genius 4015 points

Other Parts Discussed in Thread: ISO7631FM, SN65HVD37, ISO7641FM

Hello, all

Now we have one inquiry regarding internal isolation distance on ISO7631FM from our customer.

Please refer to the item below, and feedback us with your comment.

Now we are looking for suit digital isolator for connecting with RS485 transceiver like SN65HVD37.

ISO7631FM seems to be suit for this case.

However, since our required internal isolation distance is at least 1mm, this device could not meet on this.

On this case, it seems that ISO7641FM is only solution if one channel is unused.

Please let us clarify whether we could select more suit solution or not.

We thank you in advance for your information.

Best regards,

over 9 years ago

0 SaranganValavan over 9 years ago

TI__Intellectual 1815 points

Okui -san,

Both ISO7631FM and ISO7641FM have more than 1 mm distance between midpoints of both the dies. But from die edge to edge they are both about 500 um. Is this what your question is about. Can you please explain why is the customer insisting on the 1 mm clearance? As far as I can tell there should be no issues because of the internal isolation.Only the package creepage should matter , which is 8.1 mm typical for these devices.

Regards,

Sarangan Valavan

0 John Griffith over 9 years ago in reply to SaranganValavan

TI__Mastermind 21326 points

Hi Okui-san,

A clearance gap of 1mm is really only comparable to opto-isolators.

The reason for this is that the breakdown voltage of SiO₂, which is what we use for isolation median, is much higher than that of other technologies. There is a quick comparison table in the wiki-note below that I wrote that shows this comparison data. But ingeneral, SiO₂ has 4 times the breakdown voltage of Polyimide, and 40 times the breakdown voltage of Epoxy. This enables our devices to have the same isolation voltage ratings as other devices with smaller internal clearance.

http://e2e.ti.com/support/interface/industrial_interface/w/industrial_interface/2605.comparison-of-isolation-technologies.aspx

Thanks,

John

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Inquiry regarding internal isolation distance on ISO7631FM