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TPS7B67-Q1: Apply external 3.3v to the output of TPS7B6733-Q1 cause chip damage.

Part Number: TPS7B67-Q1


     Customer's board used TPS7B6733-Q1 to supply power for mcu. In production line they should program firmware to mcu, so they apply an external 3.3v to mcu.

This cause the TPS7B6733-Q1 broken.

My question is if input power from vout and the voltage not over the absolute maximum rating,whthere damage the TPS7B6733-Q1?

  • Hi Jeff,

    TPS7B67-Q1 does not have a dedicated reverse current protection circuit. While the pass element has a body diode that will allow reverse current to flow, this is a parasitic diode and is not characterized. As with any linear regulator that does not have a dedicated reverse current circuit, if you expect Vout to exceed Vin in your application you should add external protection for the reverse current.

    The two most common methods to add reverse current protection to an LDO is to either place a Schottky diode from OUT to IN or to place a diode in series with the LDO before the LDO input capacitor.

    The Schottky diode provides a robust path for the reverse current in the event that Vout should exceed Vin. The low forward voltage of a Schottky diode allows for the external diode to begin conducting before the internal parasitic body diode.

    A series diode before the input capacitor of the LDO will prevent reverse current from flowing upstream past the LDO. The diode must be placed before the input capacitor of the LDO so that any reverse current through the LDO will charge the input capacitor and raise the voltage local to the IN pin of the LDO. Once Vout no longer exceeds Vin reverse current will not flow.

    Very Respectfully,