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TPD4E1U06: Battery powered device: Where to dissipate to?

Franz Schellhase
Expert 3605 points
Part Number: TPD4E1U06

Hi Team,

My customer needs to comply with IEC 61000-4-4 in a battery powered device. Since this doesn't have an absolute ground they are wondering how to best dissipate surges. Do you recommend to connect the diodes to metal foil in the case or do you have a better suggestion?

Thank you,

Franz

  • +1
    TI__Expert 8471 points

    Hi Franz,

    For battery powered systems with no direct connection to earth, a properly optimized ground scheme is important to ensure system level robustness from high voltage transients like ESD, EFT, and surge. If possible, I would connect the protection diode to the chassis ground if you have one. A good chassis ground will be able to dissipate the transient power without significantly raising it's voltage potential. Some energy will be dissipated as heat and the rest will discharge to earth over time via capacitive coupling. If no chassis ground is available, multiple ground planes connected by stitching vias are also acceptable and will behave the same way. I recommend reading the ESD Layout guide app note for more details on this. 

    https://www.ti.com/lit/an/slva680/slva680.pdf?ts=1638979634484 

    Regards,

    Matt Smith