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CSD19533Q5A: Over 231A I_DS, a single pulse whose width is 2us acceptable?

Hisao Uchikoshi
Genius 13530 points
Part Number: CSD19533Q5A

Hi Experts,

My customer is asking about the peak I_DS. There is a chance that a I_DS flows over 231A which violates abl max of this FET when a failure occurs. Customer wants to know if this pulse peak current is acceptable.

Below is the detail condition.

V_DS : 48V

I_DS(continuous) : 2.5A

H bridge for motor (inductive load) so four FET are used in a system.

Pulse width : 2us => This is the delay when system detects an over current then shut off a FET. Once a failure is detected, the system does not continue to run so only a single pulse is applied.

I_DS at short : possbile to flow over 231A, not sure how much the curernt flow.

Is this acceptable?

Regards,

Uchikoshi

  • 0
    TI__Expert 6855 points

    Uchikoshi san,

    Thanks for the interest in  our FETs.

    The customer needs to use the transient thermal impedance  (fig1 in datasheet) to understand if they are violating the datasheet specification.

    For this they will need to understand the max pulsed current (not simply >231A), then de-rate the current based on duty cycle and pulse duration. Above you give duration of 2us but no duty cycle or max current.

    An explanation on how to use these curves is here: https://e2e.ti.com/blogs_/b/powerhouse/posts/understanding-mosfet-data-sheets-part-4-mosfet-switching-times

    I suspect your customer is violating the datasheet max's but until they confirm the missing datapoints and calculate this themselves

    Thanks

    Chris

  • 0 in reply to Chris Bull
    TI__Genius 13530 points

    Hi Chris,

    Thank you so much for your explanation and e2e link. The question from customer is the case when the short event occrus so I am guessing this conditon can be considerd as a sinlge pulse whose pulse duration is 2us. In this case, I_DS can be relaxed as shown in figure 1 of blog link, which may be higher than 231A. Is this understanding correct?

    Customer does not evalute FET yet so the actual max current will be measured.

    Regards,

    Uchikoshi

  • +1 in reply to Hisao Uchikoshi
    TI__Expert 6855 points

    Uchikoshi san,

    Yes you are correct, the pulsed rating in the datasheet is based on 100us pulse with and Rth of 1.3degC/W, <1% duty cycle. As this is a calculated value, if the customers conditions are less strenuous then the calculated pulse rating will increase.

    However, as the article states, the customer needs to remain within the SOA, which may limit the pulsed current rating.

    I would be amazed if the customer exceeded 231A with only a 2A continuous supply, I think this highly unlikely.

    Thanks

    Chris