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UCC28070: Support for AC530V Input

Conor
Guru 10495 points
Part Number: UCC28070

Tool/software:

Hi,

I am currently evaluating the UCC28070 for use in a PFC application with an AC input voltage range of 200V to 480V and a maximum input voltage of 530V. For an AC input of 530V, the rectified DC voltage will reach approximately 750V (530V × √2). While the UCC28070 itself does not directly handle high voltages, can you confirm that the IC can support this level of input voltage through proper external circuit design?

I look forward to your response.

Thanks,

Conor

  • 0
    TI__Mastermind 45700 points

    Hi Conor,

    Yes. With proper component selection, the UCC28070 can be used on higher voltage buses. 

    I hope this answers your question.

  • 0
    TI__Mastermind 35040 points

    Hello Conor, 

    Yes, the UCC28070 PFC controller should be able to work in this situation with suitable resistor-dividers on VINAC and VSENSE inputs. 

    Vin max at 530Vac is about 480Vac +10%, so I assume that the low end of the input range would be 200Vac -10%. 
    The ratio of 530V to 180V = 2.944 which is slightly less than the ratio of 265V/85V = 3.117, so the quantized feed-forward feature of the UCC28070 should work over this high-voltage range the same as if the input was 85Vac~265Vac.  

    I suggest to set Vout to be at least 770Vdc, maybe a little higher, to provide enough demagnetization voltage across the inductor at the peak of 530Vac.

    Regards,
    Ulrich  

  • 0 in reply to Ulrich Goerke
    Guru 10495 points

    Hi Ulrich and JCHK,

    Thank you for your comment！

    While the datasheet and application notes primarily describe usage scenarios around 300W, we are considering using the UCC28070 in a system with a target output power of approximately 3300W.

    Could you please clarify if there are any specific challenges or limitations when using the UCC28070 in such high-power applications?

    Additionally, are there any recommendations or design considerations (e.g., thermal management, component selection, or control adjustments) that we should keep in mind to ensure stable and efficient operation?

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Mastermind 35040 points

    Hello Conor, 

    The UCC28070 is best suited for PFC applications in the multi-kW range.  UCC28070 can be used at low power, too, but it is more complicated than necessary for this power level. 
     
    The datasheet and application notes focus on 300W, simply because of the ~300W EVM (EValuation Module) that is available to demonstrate the interleaving and other capabilities of the controller.  300W was chosen for the EVM (rather than >1kW, for example) in order to keep the size and cost of the EVM down to a reasonable level.  

    There are no special consideration or design constraints for high power different than those for low power.  If Pout is the only variable, almost everything scales with the power level. 
    If 300W has 10W overall losses, 3kW will have ~100W overall losses.  Currents will be 10:1, too.  

    Not everything is scaled exactly with the power.  High power components (inductors, capacitors, heatsinks, etc) will be larger, but maybe not 10X larger. 
    High power may use high-voltage input only, not wide-range 85Vac~265Vac, for example. 
    Very high power may use forced air for better cooling.  

    But the operating principles, design procedure, and many control parameters are basically the same regardless of power level. 

    Special considerations are needed when input voltage falls outside of the usual 85Vac~265Vac range, as in this thread.
    But since the Vin min/max range scales the same as 85Vac~265Vac, I think there should be no problem using the normal design procedure. 

    Regards,
    Ulrich