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LMR16006Y Reverse Current

Hello everyone,

Please consider we have an LMR16006YQ5 setup to supply 5V from Battery voltage input (6V-45V).

We have a fault condition where, through a 4.7K Ohm resistor, the 5V rail may be pulled up to the battery voltage, as shown here:

This would cause a reverse current of ~4mA to flow back through the buck converter.

Also note that this could be happening during a very light load condition, where the buck converter is supplying less than 30uA.

Q.)  Will this cause damage to the buck converter?

Best wishes, 

Tony

  • When the output voltage is pulled up by another supply, if the voltage is higher than VIN, reverse current will flow through the body diode of the internal MOSFET. I don't think 4mA will damage the FET. If you can add another component, you can add a small schottky diode in parallel with MOSFET body diode to redirect the reverse current to the external schottky diode. Since the forward drop voltage is smaller than that of the body diode, the schottky diode will turn on first when reverse current exists.

    regards,

    Yang

  • Hi Yang,

    Would this be a small schottky diode with anode on VOUT and cathode on VIN?

    If we had a diode from VBATT to VIN for reverse polarity protection, would we then connect the schottky cathode to VBATT, or still to VIN?

    Thanks.

  • Yes, please connect a small schottky diode with anode on VOUT and cathode on VIN. It should be connected to Vin, not Vbatt_24V, since the LMR part is connected to Vin. The goal is to protect the part. -Yang