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LM5060: LM5060 for short circuit detection

A.M.
Prodigy 110 points
Part Number: LM5060
Other Parts Discussed in Thread: LM5069

Hi, 

Considering information given sections 8.1.5 and 8.2.1.2.3 of LM5060 datasheet, an overcurrent is detected if the difference between SENSE and OUT pins exceeds the VDSTH during configurable VDS fault delay. In this case the external MOSFET is turned off and its gate is discharged at a  80 mA rate.

As VDSTH threshold is related to the overcurrent limit. When an overcurrent is detected, does LM5060 limits the output current to the overcurrent limit? I mean, does LM5060 limits the output current during VDS fault delay before switching off the MOSFET? 

Thank you in advance.

  • 0
    TI__Expert 5940 points
    A.M.

    No, the LM5060 does not limit current. It only times out. It is not a good choice if full short circuit protection is required as the FET would likely be damaged. The LM5069 has Power Limit (SOA protection) and Current Limit for the FET and is much better if you need to survive short circuit.

    Brian
  • 0 in reply to Brian Daugherty
    Prodigy 110 points
    Hi Brian,

    Thank you very much for your quickly response.

    So, in case LM5060 is used and an overcurrent is detected, I need to choose an external FET able to withstand such current , is it right? Or do I need to configure a shorter VDS fault delay ?


    Thanks a lot
  • 0 in reply to A.M.
    TI__Expert 5940 points
    A.M.

    The LM5060 depends on line impedance to limit current rise time and also peak current for severe over current conditions. If the 'short' is a high Z short, such that peak current isn't much over the detection point (which has a very wide tolerance given it is FET Rdson dependent), then it can survive - but that is a very rare design that can do this. The real purpose of the LM5060 OCP is to detect a 'mild' over current, time out the timer and shutdown. It provides inrush control, ov, uv, PG. It is meant for systems that do not need short circuit or power into short circuit protection without a fuse in line to end a bad situation. See DS section 8.1.5 for the OC fault description. The LM5069 offers complete protection.

    Brian
  • 0 in reply to Brian Daugherty
    Prodigy 110 points

    Hi Brian,

    Thank you very much for all your help.

    Regards