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TPS7A1633 / IEC ESD test

S.Satoshi
Guru 21685 points


Hi,

Now our customer is mounting TPS7A1633 on their PP board and performing IEC ESD test. They need to pass 8kV testing but the TPS7A1633 is latched and the output keep low at 7kV testing. They connected EN pin to VIN directly, and so they tried to add 100ohm between EN pin and VIN, then they can improve ESD tolerance. So it seems that this latching is happened due to effect via EN pin. So can you please give you comments for following questions?

1, Can you recommend to add 100ohm between EN pin and VIN to improve ESD tolerance?

2, Do you have other work-around to improve ESD tolerance?


Best Regards,

Sonoki / Japan Disty

  • 0
    TI__Expert 3300 points

    Hi Sonoki,

    Thank you for your post. The TPS7A1633 is not rated for such high ESD ratings. In order to use this part with high system level ESD as discribed by you, an ESD suppression diode will be required. What is the input voltage to your LDO? Below is a link to some ESD protection solutions offered by TI:

    http://www.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=1444&uiTemplateId=NODE_STRY_PGE_T

    Hope this helps.

    Regards,

    Kartik

  • 0 in reply to Kartik Sinha
    Guru 21685 points

    Hi Kartik-san,

    Thank you for your quick response.

    I will promote the ESD protection solution you informed. The input voltage in their system is 42V(max) which is the voltage of Li-Ion with 10 series configuration.

    In addition to promote ESD protection solution, I would like to provide some reference information to reduce ESD level in system level. I believe that to add RC filter on EN pin will be effective to reduce ESD level at EN pin. Are you agree with my understanding?


    Best Regards,

    Sonoki

  • 0 in reply to S.Satoshi
    TI__Expert 3300 points

    Sonoki-san,

    Yes an RC filter can be used to protect the EN pin from surges however this may not be effective at the ESD levels you mention. Please see below for a suggestion on the RC filter:

    Please note, that this will effect the rise time of the EN pin signal. Rise time will be ~ 2.2 * R * C

    More suggestions are shown below:

    Over here a 10 Ohm current limiting resistor is used. The  Schottky diode protects from negative voltage spikes. The Tranzorb (Zener symbol) adds protection against positive spikes and the RC filter is also present. The rise time for the Enable pin will be a lot slower thus affecting the start up time of the LDO.


    Hope this helps.


    Regards,

    Kartik

  • 0 in reply to Kartik Sinha
    Guru 21685 points

    Hi Kartik-san,

    Thank you for your suggestion. I will suggest these solution and leave a decision up to our customer. I close this thread so far but please let me ask again if additional question will be received from them.


    Best Regards,

    Sonoki