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UCC25630-1EVM-291: UCC25630-1 EVM AC power?

Gerrit Barrere
Expert 1245 points
Part Number: UCC25630-1EVM-291
Other Parts Discussed in Thread: UCC256301

The schematic for this EVM (pg 8 of User Guide http://www.ti.com/lit/pdf/sluubq8 doesn't show any way of connecting the AC input bridge D3 to the LLC power stage.  I don't see how an AC input could be tested.

The User Guide says to connect both AC and DC inputs and apply power to both, which doesn't make much sense either.  It seems like there should be a jumper from D3 pin 1 to J2 for AC testing, and only one or the other of a DC or AC source should be connected.

Am I missing something?  How does this work?

  • 0
    TI__Mastermind 27095 points
    Hi Gerrit,

    Thanks for your interest in the UCC25630-1EVM. The EVM by default comes with UCC256301 which has an X cap discharge feature. The UCC256301 controller monitors the AC line through its HV pin and when the AC line is removed, the controller discharges the line to line capacitance. The LLC stage itself is designed to operate with a 340V to 410VDC input.

    The HV pin of UCC256301 should not be connected to a DC input as it will not be able to sense a zero crossing on the HV pin and will continuously try to discharge what the controller thinks is the line to line capacitance.

    The design of the EVM itself is to mimic an AC to DC system where the input to the LLC is a high voltage PFC bus and the HV pin of UCC256301 monitors the AC line.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Expert 1245 points
    OK, thanks, that makes sense. It seems like an explanation like this should appear in the User Guide, though.

    Regards,
    Gerrit