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App note: Automotive power circuit handles interruptions and 72volt spikes

Posted on Saturday, June 4th, 2011 in app notes by Ian

rsdio writes:  More good ideas to steal and repurpose

This circuit maintains power to the load regardless of momentary shorts or opens in the supply voltage, and includes a low-current overvoltage-protection IC (MAX6495) that protects the load against transient voltages up to 72V.

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4 Responses to “App note: Automotive power circuit handles interruptions and 72volt spikes”

  1. Paul says:

    Q1 & Q2 are opposite polarity, but have the same part number. Likewise for Q3 & Q4. Hmmm…

  2. Token says:

    Would this still require a Schottkey diode for reverse voltage protection?

  3. rsdio says:

    I don’t think you necessarily need a Schottky for reverse-voltage protection – any diode should do. The Schottky has a low forward-voltage drop, but there are other LDO diodes out there.

    If there is a chance that the input will have reverse polarity, then you should check the MAX6495 data sheet for voltage tolerance on the pin 1 input. Q1 and Q3 should handle negative voltages, but I can’t be sure without checking their data sheets, too.

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