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

over 8 years ago

0 JohnTucker over 8 years ago

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 Satoshi over 8 years ago 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 JohnTucker over 8 years ago 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.

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