TPS561201: VFB accuracy vs Vo value

Hi,

The VFB accuracy slightly impacted by Vo value as it's DCAP2 control mode. 

Hi,

Do you know a material for explanation of VFB accuracy and Vo at DCAP2?

Best regards,

Shotaro

Let me check it and share you later....

Did you find any material?...

Hi

I believe VFB on the datasheet means "Voltage Reference" (=VREF) in the below diagram.

On the other hand, the AN explains error of "Emulated Ramp Generation". So I think the AN is not related to VREF accuracy.

Hi 

Internal Vref is accurate and stable, it's Independant on Vout value. customer can't measure it.

The VFB voltage on FB pin equal to internal Vref at normal operating.

DACP control mode inject ripple on VFB for proper On/Off control, so VFB accuracy is quite different from Vref accuracy. 

Hi

What is guaranteed by the values? In my understanding, this is corresponding to Vref accuracy. I am not sure meaning of the value...

Original question is that the datasheet spec is under Vo=1.05V and the value is changed or not due to Vo setting.

Hi,

as explained on the AN SLVA762A:

VFB voltage on FB pin always has offset voltage to internal Vref on DCAP2 control mode, the VFB voltage is slightly changed with Vo setting because the ripple is related to Vin-Vo voltage

Hi,

I understood what you say. Can you review if my understanding is correct?

VREF: fixed value.

VFB: The value is changed by Vout value. And Vout is determined by VFB. So VFB accuracy is equal to Vout accuracy. Do we have any data for VFB vs Vout?

Hi,

You understanding is correct.

Seems you still mix the Vref and Vfb if you ask for any data for VFB vs Vout, you can see that VOUT and VFB voltage almost have same accuracy as they have fixed ratio on above equation.

VOUT_target=Vrefx(R1+R2)/R2, Assume Vref=Vfb at Vout=1.05V. then at other Vout voltage, VOUT_target has small offset to actual VOUT which is the data you are caring about. we didn't check this offset vs Vout as it depends on actual application design.

Hi,

OK, VFB has offset voltage created by ripple generator. And this ripple voltage is changed by Vout setting. If the sentence is not correct, please tell me...