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ISOW1432: Layout Suggestion

Subash Kumar
Prodigy 80 points
Part Number: ISOW1432


Tool/software:

Hi,

I am using multiple transceiver in my product and due to space limitation i had placed transceivers in both sides of PCB back to back.

As this transceiver contain DC to DC power stage, Which can radiate high frequency noise throughout the PCB dielectric.

My Question is, Can we place the transceivers by this way with any implementation in stackup level.

Thank You

  • 0
    TI__Expert 8430 points

    Hi Subash,

    Thank you for reaching out.

    This is indeed an interesting approach you have here but we do not recommend two ISOW devices in such close proximity because one ISOW device can interfere with another's operation here.

    On the stakcup detail, I don't have any proven solution to share here as this has never been tested this way but there's definitely a risk of EMI between the two ISOW1432 with standard FR4 PCB material.

    One Suggestion that I can think of is adding a shielding layer in between the two devices on the PCB

    Regards
    Varun
  • 0 in reply to Varun Kumar
    Prodigy 80 points

    Hi Varun,

    Thanks for the reply.

    Is it recommended to place a ground shielding ? 

    Also what is the safe gap between transceiver when they are on same side of PCB.

    Thanks

  • 0 in reply to Subash Kumar
    TI__Expert 8430 points

    Hi Subash,

    Please find my inputs below.

    Subash Kumar said:
    Is it recommended to place a ground plane below the transceiver ? 

    The term transceiver is a bit ambiguous here from Isolation point of view. If you're using this device for Isolated power supply and have a HV requirement across two GND as well, which you didn't mention before, then definitely NO, you can not put any of the two grounds below the ISOW1432 device. Apologies for the confusion here.

    Subash Kumar said:
    Also what is the safe gap between transceiver when they are on same side of PCB.

    There is no specific layout guideline for the safe gap so I cannot quote an exact number here, but 5mm is more than enough to be risk free. The ISOW1432 is capable of being immune to radiation noise of up to 15V/m so the device being adjacent to each other should not pose a threat to functionality.

    Hope this resolves your query.

    Regards
    Varun