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TPS25921A: surge characteristic issue

TS Yang
Genius 4800 points
Part Number: TPS25921A

Hello,

I have several questions at TPS25921A test as below.

1. Even in the same LOT part, the durability variation of single item is severe. Is there any spec at TI?

2. Does TI have countermeasure for surge?

TS

  • 0
    TI__Guru* 95911 points
    Hi Yang,

    Can you please elaborate... what kind of variation between the devices is observed? which parameter of the device?

    Please help with more information on
    what is the end equipment? where does this device placed in the system .. at the input side or after the power section?
    Operating voltage?
    what level of surge protection your system need?

    Best Regards,
    Rakesh
  • 0 in reply to Rakesh
    Genius 4800 points

    My question is about TPS25921A durability.

    I found the part to part variation at surge test.

    Some can endure more than 4kV, but others burnt below 2kV.

    For your information, the end equipment is face discriminator.

    below is schematic around TPS25921.

    Operating voltage is 12V.

    In front of input of TPS25921 is the common circuit of this application,

    but if you can recommand other protect circuit, please share for me.

    We need at least 2kV level of surge protection.

    thanks,

    TS

  • 0 in reply to TS Yang
    TI__Guru* 95911 points
    Hi Yang,

    Thanks for the details.
    VR7, VR8 (SFI1210SN750-060K) has breakdown voltage of 75V and might not be acting when needed.
    We recommend to use TVS diode right at the input of TPS25921 device. The preferred part no. is SMBJ17A-13-F. Please check by doing these modifications.
    what is the value of C5 in the schematic?

    Thanks
    Rakesh
  • 0 in reply to Rakesh
    Genius 4800 points

    Hi Rakesh,

    thanks for your quick answer.

    About TVS diode, we have two solution - Littlefuse and FEIDA.

    SMBJ15CA and SMBJ15A , which one is better?

    I have one more question.

    When TPS25921 get damaged from high energy such as Surge, a fire break out from TPS25921.

    Not just device destroyed, catch on fire.

    I'd like to know your idea about this.

    TS

  • 0 in reply to TS Yang
    TI__Guru* 95911 points
    Hi Yang,

    SMBJ15A should be good enough here.
    The high energy surge could result in excessive current through the device and intense power stress across the device. There can be cumulative effect as well, due to rise in voltage at the input of the device.

    Regards,
    Rakesh