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ISOW1432: Schematic Review

Bekir KÖR
Prodigy 80 points
Part Number: ISOW1432
Other Parts Discussed in Thread: ISOW7741DFMEVM

Tool/software:

Dear All

Can you review the attached schematic for the ISOW1432DFMR that I use on the RS485 interface of my sensor board?

Should the references of TBU-RS055-300-WH and TISP4350H3BJR-S that I use here for protection after isolation be ISO_GND or GISOIN?

The same question applies to LTV-817S and TS5A3166DBVR.

So should I use ISO_GND on GND2, the reference of VISOOUT, or GISOIN, the reference of VISOIN, as reference after the isolator?

Also, is there anything missing, wrong or needs to be improved in the design?

  • 0
    TI__Expert 7585 points

    Hi Bekir,

    Thanks for reaching out. Please find my inputs below:

    1. The reference for secondary side components should be GISOIN and not ISO_GND.
    2. Connect GNDIO to GND and not GND1.

    I don't se any other shortcomings here.

    Regards
    Varun

  • 0 in reply to Varun Kumar
    Prodigy 80 points

    Hi Varun,

    Thanks for your quick response.

    I have quoted connecting GNDIO to GND1 from ISOW7741DFMEVM user manual and ISOW1432DFMR datasheet, images are below.

    Can you explain why I should connect it to GND?

  • +1 in reply to Bekir KÖR
    TI__Expert 7585 points

    Hi Bekir,

    Apologies for the confusion here. I did not mean my second comment in a negative way.

    The schematic will work absolutely fine, it's just that connecting the GNDIO after ferrite bead can give you marginal improvement in emissions that's it.

    Regards
    Varun