ISOM8110: ISOM8110 Copper under the part

Tharaka Goonetilleke

Part Number: ISOM8110

Tool/software:

Hello,

The Digital Isolator Design Guide recommends no copper underneath the device. However, I cannot find any reference to this in the datasheet for ISOM8110 Opto-Emulator, which is essentially a digital isolator. Should I leave all layers underneath copper free or is it OK to have respective ground planes with a gap (say 25mils/0.635mm)? My signals are discrete signals (no communication, just ON/OFF 20milliseconds apart), switches a couple times during the operation. What would be the best approach?

Thank you,

Tharaka Gooentilleke.

19 days ago

0 Andrew J 19 days ago

TI__Mastermind 24535 points

Hello Tharaka,

Thank you for reaching out. The device will still operate if there are metal layers under the device. However, for best isolation performance, it is recommended to have an all-layer keep-out zone between the isolated and non-isolated side of the isolator. The ISOM8110DFGEVM would be a good example of an isolated layout.

Best,
Andrew

0 Tharaka Goonetilleke 19 days ago in reply to Andrew J

Prodigy 40 points

Hi Andrew,

Thank you! Would keeping copper underneath increase EMI by any chance?

0 Andrew J 19 days ago in reply to Tharaka Goonetilleke

TI__Mastermind 24535 points

There is not an EMI concern here. The concern is that if copper is placed underneath the isolator that it will compromise the isolation ratings of the application.

It would be okay to place copper under this isolator if your application isn't required to pass the full isolation rating.

0 Tharaka Goonetilleke 19 days ago in reply to Andrew J

Prodigy 40 points

Thanks Andrew. This addresses my concern. I will mark the issue as resolved.

Thanks again.

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ISOM8110: ISOM8110 Copper under the part