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Relation of VFB and Vout/Vin duty (TPS54227 and TPS51367)

Satoshi
Guru 19575 points
Other Parts Discussed in Thread: TPS51367, TPS54227

Customer is worried about Vout(VFB) transition(change) depend on Vout/Vin duty cycle.

Is there following relation gragh?

If have these gragh, please give me. 

①TPS51367

　・Relation gragh of Duty cycle and Vout transition

②TPS54227

　・Relation gragh of Duty cycle and VFB transition

　・Or, VFB of below condition

　　1. 12Vin⇒1.1Vout

　　2. 12Vin⇒3.3Vout

　　3. 12Vin⇒5.0Vout

 

Best regards,

Satoshi

  • 0
    TI__Guru**** 191445 points

    I am not sure what you are asking.  Duty cycle is not directly related to VFB.  Duty cycle is approximately equal Vout / Vin so:

    1.  D = 0.092

    2. D = 0.275

    3. D = 0.417

    Let me know if you have clarification.

  • 0 in reply to JohnTucker
    Guru 19575 points
    Jorn Tucker-san

    Thank you for reply.
    Customer want to know VFB change.
    I think that hysteresis comverter's VFB is depend on Duty cycle.
    (A little change)
    -------------------
    1. D = 0.092
    2. D = 0.275
    3. D = 0.417
    -------------------
    VFB is a little difference 1~3.

    But D-CAP's VFB-change is smaller than COT DC/DC (competitor).
    There is a need to prove it.

    Best regards,
    Satoshi
  • 0 in reply to Satoshi
    TI__Guru**** 191445 points
    Why would you think that? Are you talking about the ripple voltage? I think the VFB valley voltage is constant at 0.765 V.