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UCC256304: UCC25630 in 800V application

Lin Zhao
Intellectual 1230 points
Part Number: UCC256304


Hi, 

My customers have some question on UCC25630 on 800V application:

They need add transform isolation between HS and MOS mid-point, is this feasible, any issue on this approach?

Could add external MOS driver to increase driving current ability during HV application?

In addition to above question, and:

What's the constant frequency during burst mode?

For 100Hz line frequency ripple, UCC25630 should have advantage on the Io ripple suppression? customer's target is 100Hz Io ripple<2%.

Thanks!

  • 0
    TI__Mastermind 27145 points
    Hi Leo Zhao,

    Thanks for your interest in UCC256304. The HS pin needs to be connected to the switch node in order for the adaptive dead time circuit to function properly. It is not feasible to isolate the HS pin from the switch node.

    The frequency in burst mode is dependent on the burst mode threshold and the resonant tank design. Because hybrid hysteretic control looks at the resonant capacitor charge, there is inherent feedforward in the control loop. Because of this, there is some advantage in the low frequency ripple suppression at the output.

    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    TI__Intellectual 1230 points
    Hi Banjamin,

    thanks, how about below question:
    Could add external MOS driver in HO/LO to increase driving current ability during HV application?
    For 100Hz line frequency ripple, UCC25630 should have advantage on the Io ripple suppression? customer's target is 100Hz Io ripple<2%.
  • 0 in reply to Lin Zhao
    TI__Mastermind 27145 points
    Hi Leo Zhao,

    Yes, it is possible to add external drivers to increase the driving current capability. You would need to use two low side drivers (half bridge driver is not possible here because HO is floating and not referenced to gnd) and an external bootstrap

    Yes, UCC25630x does have some advantage in suppressing low frequency ripple at the output because of the inner charge loop incorporated into hybrid hysteretic control.

    Best Regards,
    Ben Lough