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UC1707: UC1707 Power Pins Reversed Bias

Michael Jackson
Prodigy 10 points
Part Number: UC1707

The Vin and Vc power pins are tied to a +28 VDC Power Supply.  Another piece of test equipment caused a -5 Volt Peak (28 VDC to -5 VDC) of duration 10 ns, -3 Volt pulse of duration of 400 ns on the Vin and Vc power pins relative to ground.  The data sheet is silent having a negative relative voltage on the power pins on the absolute maximum ratings, although recommended operating conditions have minimum of 5 V.  It looked like one of the three parts stopped drawing current until power cycled.  Normal current draw 50 mA, anomaly was 30 mA.  Board is fully functional after power cycling.

Can the UC1707 tolerate this kind of negative pulse or should these parts be replaced (overstress for a space application)?  Can transients keep the part from drawing power?

Thank you in advance,

Michael A. Jackson

  • 0
    TI__Mastermind 28645 points

    Hey Michael,

    Generally the reason for not having negative voltage on the Vcc is because of the ESD protection diode.

    Its possible this was damaged during the transient. I would be worried that the ESD diode was reversed bias and ended up drawing current.

    Thanks,

    Daniel