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LM7310: Peak current handling

Wei-Han Lai
Prodigy 50 points
Part Number: LM7310

The current consumption waveform for our system is shown in the attached picture. As seen in the scope shot, there may be current spikes up to around 12A, but the average current consumption is around 1.5A. The LM73100 is rated for 5.5A continuous and has a "fixed fast trip current threshold" of 21.9A, so my understanding is that as long as our current spikes stay below 21.9A, the LM73100 should be able to handle our system's current profile, since the average continuous current in our system is 1.5A and the part is rated for 5.5A. Please confirm whether the LM73100 can handle the current waveform shown and operate continuously.

  • 0
    TI__Mastermind 38985 points

    Hi Wei-Han,

    Since the current is not exceeding the fast trip threshold, device won't perform the fault response. What is causing this kind of current profile? The device should be able to handle the transient currents, but it looks like they are very frequent. I will have to check internally with designer if the device can handle this current profile.

    Please inform me about the cause of this current profile and end application. 

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    TI__Mastermind 38985 points

    Hi!

    I have another question. Please tell us about the transients profile? transient duration and time difference between the transients.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    Prodigy 50 points

    The cause of this current is when we are running the servos. Our end application is a small aerial plane.

    Unfortunately I do not have accurate information on the profile of the transients and cannot easily recreate the test due to the system being under build. To estimate, I would say the time period is about 130ms between transients. The base of the transient is probably 20ms in duration and then as current goes higher the duration decreases exponentially at the higher current levels.

  • +1 in reply to Wei-Han Lai
    TI__Mastermind 38985 points

    Hi Wei, 

    Since the average power dissipation is low and there shouldn't be any concern. I would recommend you calculate the FIT rate for reliability. This App note will help you in that.

    App note: Calculating FIT for a Mission Profile

    I am closing this thread. Click resolved to close it from your side also. You can always reply here to reopen the thread for any follow up questions.

    Best Regards,
    Arush