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LM5060: LM5060 Short Circuit Current Protection

Jessica Riley90
Prodigy 180 points
Part Number: LM5060
Other Parts Discussed in Thread: LM5069

Hello, I've seen in a number of posts that the LM5060 is not recommended as a method to provide over-current protection but it is unclear to me why that is the case.  From section 8.1.5 in the datasheet, the overcurrent fault detection seems like it should provide protection in the case of a hard short circuit by monitoring the voltage drop across the FET.  I understand that the factors here are the time it takes to turn off the FET (dependent on the capacitor at the TIMER pin), the variation in Rdson of the FET, and the ability of the FET to handle the maximum possible short-circuit current for the given response time.  But if all of those are sized correctly, is there any reason this device cannot be used as a short-circuit protection switch?

I understand the LM5069 is recommended for over-current protection as it provides current limiting in the case of over-current as well as short circuit protection, but the quiescent current for the LM5069 is much too high for my battery application.  I am hoping the LM5060 will be sufficient as a short-circuit-only protection device.

Thanks,

Jess

  • 0
    TI__Expert 5940 points
    Hi Jessica,

    The LM5060, as you note, does not limit current or provide SOA protection for the FET. So there is nothing to limit peak current in the FET during a short circuit other than line impedance. Current protection is only a timed out over-current detection based on FET Rdson which can have up to 3:1 variance over temp and FET to FET tolernance. Essentially, you are completely dependent on high line impedance, and short timer for any protection from short circuit. The device is essentially: OV, UV control + inrush control + limited over current in a timed circuit breaker mode. It can be used in reverse input voltage protection per the DS apps.

    Brian
  • 0 in reply to Brian Daugherty
    Prodigy 180 points

    Thank you for the feedback.  I think this device will work in my application, I just wanted to be sure I wasn't missing something given all the comments about this part.