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UCC28950/about inductor current dispersion in interleave

Tsukui Yusuke
Guru 21930 points
Other Parts Discussed in Thread: UCC28950

Hi,

Could you tell me about inductor current dispersion in interleave.
Customer is troubled with the dispersion of the inductor current.
I have got three questions from customers.

1.Which parameter influences the dispersion of the inductor current?
2.Could you tell me Information with the dispersion of the inductor electric current?
3.DC offset voltage seem to affect the inductor current.
    Please tell me the variation of this offset voltage(typ=0.85V).



Please give me some advice.

Best Regards,
Yusuke/Japan Disty

  • 0
    Guru 21930 points

    Hi,

    Can I get the information ?
    If you need more information or if  I should  clarify my comment ,
    please let me know.
     
    Best Regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 25570 points
    Hello Yusuke-san
    I don't understand what you mean by ' inductor current dispersion in interleave' - is it something to do with operating two UCC28950 devices in a master / slave configuration ?

    I'm sorry but I don't have any information about the variation (dispersion?) of the 0.85V offset. In any case, variations in the CS offset (0.85V) won't affect the inductor current because the outer control loop will settle at a level that demands the correct current to satisfy the load condition. If the CS amplifier offset is a little high, the control loop (COMP) will settle at a level that is a little higher, if its a little low the control loop (COMP) will settle at a level that is a little lower. the COMP pin will settle at a level such that the EA+ and EA- inputs are at the same level. The error amplifier input offset (±7mV), the accuracy of the REF output (1.5V) and the accuracy of the output voltage potential divider will all contribute to the error in the output voltage setpoint.

    Regards
    Colin
  • 0 in reply to Colin Gillmor
    Guru 21930 points

    Colin-san,

    Thank you for your kind support.
    I am sorry for not explaining sufficiently.
    Customer use two UCC28950 devise in master/slave configuration.
    I wanted to tell the dispersion of the inductor current occurs between two devices.

    Best Regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    Guru 21930 points

    Colin-san,

    Let me ask you one more thing.
    Could you tell me the recommendation circuit when customer use UCC28950 in interleave?
    Customer use master side comp voltage as buffer of slave comp voltage.
    Is this how to use a correct answer?

    Best Regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 31580 points

    Hi Yusuke-san,

    Why does the customer want to connect the COMP pins in parallel? Is it to provide a form of current sharing?

    In the introduction section of the slua609 it states that the UCC28950 does not have a load sharing control capability.


    Regards

    Peter

  • 0 in reply to Peter Meaney
    Guru 21930 points

    Peter-san,

    Thank you for your support.
    There are following mentions in UCC28950 data sheet.
    Customer want to know the recommended circuit of this.
    Could you tell me about recommended COMP and SYNC pin circuit in interleave condition.



    Best Regards,
    Yusuke/Japan Disty

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 31580 points

    Hi Yusuke-san,

    There is an e2e post that shows how to connect the error amplifier circuits for the master and slave.

    e2e.ti.com/.../161691

    The sync pin connections are covered by the datasheet on page 26.

    Regards

    Peter

  • 0 in reply to Peter Meaney
    TI__Mastermind 25570 points

    Hi Yusuke-san,

    Please let me know if you need any further information on this -

    Thanks

    Colin

  • 0 in reply to Colin Gillmor
    Guru 21930 points

    Colin-san,

    Thank you for your comment.
    Can you be a bit more specific about interleave circuit?
    I was confirmed in the past posts, but it does not come up with a circuit of the image.
    Could you tell me about schematic diagram that connects the two of UCC28950?
    There is one other thing,Is the current share possible?
    (Customer is troubled. Because inductor currents are different between two UCC28950.)

    Best Regards,
    Yusuke/Japan Disty