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UCC1804 max. Vcc

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Intellectual 460 points
Other Parts Discussed in Thread: UCC1804

UCC1804 start-up voltage (Turn-on threshold) is 12.5v, but Absolute Max. Ratings for Vcc is 12.0v.  What is the real Max. Vcc ?

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    TI__Genius 15910 points

    Excellant question!  As a rule we never want to go near the ABS MAX rating of a device but that seems to be a problem here.  I have submitted the issue to sustaining and will respond as soon as they reply.

  • 0 in reply to Lisa Dinwoodie
    TI__Genius 15910 points

    That data sheet was written to cover a wide range of devices in that family so it does get confusing when it comes to the ABS MAX ratings.  For the devices that have a turn on threshold greater than the 12.0V maximum given in the table, VCC  must be powered through a current limiting resistor so that ICC is less than 30mA.   The VCC of the UCC1804 obviously needs to be at least as high as the UVLO start threshold of 13.5V but the current on VCC needs to be limited to less than 30mA so that the internal 13.5V clamp does not sink excessive current and cause device heating resulting in reliability issues.