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LM74700-Q1: EN_pin usage

Lanxi Li
Expert 5415 points
Part Number: LM74700-Q1

Hello teams,

My customer is conscious about the usage of EN_pin. We know that the EN_pin always needs to be on operation so that LM74700 can work well.

But, if there are any other application cases, that we can let the EN_pin off to help get a better use.

Thanks for your supporting.

Best regards,

Lanxi Li

  • 0
    TI__Expert 3370 points

    Hi Lanxi,

    When the EN is pulled low, the internal gate driver is disabled. So, the external FET cannot turn ON and remains off. Then, the body diode of the external FET conducts forward current and blocks the reverse current. So in such a situation the forward current will flow through the body diode and the diode's forward voltage drop will then affect the power efficiency of the system in a negative way. Hence, in general, this mode of operation is not recommended when the system is supplying power to the downstream loads.

    The EN feature is present because disabling the device when not needed would reduce the amount of power the IC takes to operate. The sleep current of the device, i.e. the current when the EN is low and the device id OFF, is only 1uA, as opposed to 80uA the IC takes during it's normal operation. So ideally, the EN pin is pulled low when the operation of the device is not required. But when the system is ON such that the downstream loads require current, the EN is always made high.

    Kindly let us know about the betterment sought by pulling the EN low. We can then revert back with a solution. Also, if possible, let us know about the customer use case and if the customer is using some other solution and wishes to replace it with LM74700.

    Thanks and best regards,

    Divyanshu