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UCC28782: What's the difference between UCC28780 and UCC28782 ?

Tak
Intellectual 480 points
Part Number: UCC28782
Other Parts Discussed in Thread: TPA3251, UCC28780, , UCC2893, TL431

I'd like to design about Audio AMP.

We will adopt TPA3251 as classD Amp.

On the other hand , I will use UCC28780 as Power supply of TPA3251.

So would you please tell me the difference UCC28780 and UCC28782 ?  (Question1)

We want to design with very compact size. So I choose UCC28780.

I understand this device is for USB PD.

But I believe UCC28780 or UCC28782 can use as audio supply (for TPA3251) . Is that right ? (Quesiotn2)

I have often used UCC2893 (PWM ACTIVE CLAMP FLYBCK) until now. But this devise is not for very compact size . 

Please advise to us.

  • 0
    TI__Mastermind 22915 points

    Hi Tak,

    Thank you for the query on UCC28780.

    Both UCC28780 and UCC28782 are optimized for offline applications. UCC28782 is the next generation of UCC28780,  it integrated all of features of UCC28780 and some new features like emi dithering, input OVP, boost inductor integration for facilitating wide input operation.

    So it really depends on your input voltage specifications. If it low voltage inputs, I would advice to PWM active clamp itself else consider using UCC28780.

    Regards,

    Harish

  • 0 in reply to Harish Ramakrishnan5
    Intellectual 480 points

    Thnak you for the reply.

    I understood the difference between UCC28780 and UCC28782.

    However I'd like to confirm the following.

    1) The difference of the PWM Active clamp flyback (like UCC2893) and the PFM Active clamp flyback  (like UCC28780) 

    2) Whether UCC28780 and TPA3251 are  a good match. (Whether UCC28780 is used for audio applications)

    Our requests are follows.

    AC85-264V

    Compact hgih-dentsity power supplies

    Non audible noise

  • 0 in reply to Tak
    TI__Mastermind 22915 points

    Hi Tak-San,

    Thank you for the reply.

    Question 2) I think from your input voltage specification of 85 to 264Vac and using TPA3251 I assume power level around 160-220W for your application. So UCC28780 should be good for this power levels. Are you generating unipolar voltage or bipolar voltage? Bipolar might suffet cross regulation.

    Question 1) I am sorry I do not know much about UCC2893. May be you can ask a separate post with UCC2893 as a product expert can help. But UCC2893 as active clamp forward should be suitable to the application. But for offline AC-DC conversion, I feel UCC28780 might be more suited.

    Please let us know if you have further questions.

    Regards,

    Harish

  • 0 in reply to Harish Ramakrishnan5
    Intellectual 480 points

    Hi, Harish 

    Thank you for the reply.

    I understood what you meant .

    Finally, I 'd like to confrim about the corss regulation.

    If possible, we would like the power supply for TPA3151 to be bipolar. (ex. ±20V)

    You said that tipolr might suffect cross regulation. 

    However, I believe that a negative feedback control from +B voltage to -B voltage would not be a problem. (like in the attached file)
    What do you think?
    If unipolar power supply is still preferable, then do so (e.g. +40V)

    What do you think?

  • 0 in reply to Tak
    Intellectual 480 points

    UCC28780, as shown in the attached file.
    Can't I get feedback control from +B to -B?

  • +1 in reply to Tak
    TI__Mastermind 22915 points

    Hi Tak-San,

    Thank you for sharing the cicuit.

    For better regulation in case of bipolar supplies, it is recommended to add a capacitor to the secondary as shown in the following references to improve regulation.

    https://www.edn.com/power-tips-85-adding-a-single-capacitor-to-improve-cross-regulation-in-dual-output-flyback-power-supplies/

    https://www.onsemi.com/pub/Collateral/TND351-D.PDF

    The above configuration which you show should work but I think it will still have poor cross regulation as leakge inductance will cause degrading regulation. But will have to study your TL431 configuration further.

    Please let us know if you have questions.

    Regards,

    harish

  • 0 in reply to Harish Ramakrishnan5
    Intellectual 480 points

    Hi , Harish

    Thank you for the valuable information.

    I will read the documents wihch you shared.

    Although the cross regulation may be poor , we can adopt  UCC28780 as bipolar power supply .

    Is that right ?

    Anyway , I'll try with bipolar power supply type.

    If additionl issue occuer , I will post again.

    Thanks.

    Tak

  • 0 in reply to Tak
    TI__Mastermind 22915 points

    Hi Tak-San,

    Please let us know if you have further questions. Yes, the documents above show a small hack for bipolar power supplies and it can be applied to UCC28780.

    Thank you

    Regards,

    Harish