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ISO7140CC: ISO7140CC GND issue

Arik Fargion
Prodigy 10 points
Part Number: ISO7140CC


Tool/software:

Hi,

I use the ISO7140CC in my design (let's define it as a closed box) and found out that from outside the 2 ground of the chip (GNDI and GNDO) are shorted.

My question is: Is there a potential damage to the ISO7140CC or that it will just not function as isolation components ?

One more question is: Let's assume no signals are connected at all and the ISO7140CC is assembled on the PCB for future function. Will this short of GNDI and GNDO will cause any damage to the ISO7140CC ?

Thanks,

  • 0
    Guru 317480 points

    According to the VIORM specification, the isolator allows offsets between −566 V and +566 V between the two sides. 0 V is inside this range.

  • 0
    TI__Mastermind 18125 points

    Hi Arik,

    Thanks for reaching out.

    Arik Fargion said:

    My question is: Is there a potential damage to the ISO7140CC or that it will just not function as isolation components ?

    If the GND1 and GND2 of the isolator are shorted, the essentially bypasses the isolation barrier. This means that there would be no isolation between side 1 and side 2.

    Arik Fargion said:
    One more question is: Let's assume no signals are connected at all and the ISO7140CC is assembled on the PCB for future function. Will this short of GNDI and GNDO will cause any damage to the ISO7140CC ?

    No, under recommended operating conditions and ratings, the device would not be damaged from tying the grounds together.

    However, by tying the grounds together, there would be no protection from side 1 to side 2 or vice versa. So if transients are applied on the system on one side, the entire system could be damaged along with the isolator device.

    The ISO7131 device is a pretty old digital isolator. TI offers newer and more up to date 4 channel digital isolators, such as the ISO6740 and ISO7740, which has lower prop delay and better overall specs. Please feel free to consider these options for your application.

    Regards,
    Aaditya V