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LMZ23610: Sync pin left floating

Marco Maioli
Prodigy 170 points
Part Number: LMZ23610

Hi

In a device delivered to the customer we left the LMZ23610 Sync pin floating.

The power supply circuit is a 24vdc input with 5Vdc out 8A.
We realized after that on the datasheet it was written to connect it to GND.
What could happen?

Thank you

Marco

  • 0
    TI__Guru 50120 points

    Hi Marco,

    The SYNC pin is most likely a high impedance pin. This means if it is left floating instead of GND when not used, it makes the pin susceptible to couple high frequency noise onto the pin. This is why the pin should be connected to GND if not used. 

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    Prodigy 170 points

    Hi Jimmy

    Thanks for the reply. If noise or high frequency to couple to the pin, could this cause instability or malfunction (e.g. voltage changes on output pin)?

    Best regards

    Marco

  • 0 in reply to Marco Maioli
    TI__Guru 50120 points

    Hi Marco,

    If high frequency / noise is coupled onto the SYNC pin, the switching frequency of the device may be impacted. Depending on the frequency, it may cause instability through current limit or a variety of other failure modes. You would need to test this out to see if this impacts your application. The noise/ surrounding frequencies might be low and small enough to not couple onto the SYNC. Having the SYNC pin grounded when not used allows for a more robust design.

    Because of this, it is recommended to have the SYNC pin grounded when not used. 

    Regards,

    Jimmy 

  • 0 in reply to Jimmy Hua
    Prodigy 170 points

    Hi Jimmy

    Thanks, that was what I wanted to know.

    Thank you

    Regards

    Marco