VFB range in power save mode for tps63020

Kocela, 

In PFM mode, the TPS63020 looks at the average inductor current. The converter stops switching when the average inductor current goes below 100mA and the output voltage is at or above its nominal value. If the output voltage drops below its nominal value, the device ramps up the output by starting operation using a average inductor current higher than what is required by the load.

Regards, 

Daniel

Your estimate is incorrect. 

The nominal regulation voltage is 495mV min, 500mV typical and 505mV max. 

In PFM, mode the output can vary between the nominal regulation voltage and about 2% to 5% above that.

The average voltage measured on Vfb would then be about 1% to 2.5% above the nominal regulation voltage. 

The 2% to 5% values are measured during test in a static condition; in an actual application these may increase due to parasitics.

You almost got it; in my statement above, I am referring to the voltage on Vfb in both cases. 

In one case, the lower and upper thresholds and in the other case the average voltage.

It should look more like as I've updated below in blue:

Kocela Chang said:

As your words, i try to write into formula as below.

In PFM

Vfb: Vfb_nom*1.02(min.) ~  Vfb_nom*1.05(max.)

Vfb_avg:  Vfb_nom*1.01(min.) ~  Vfb_nom*1.025(max.)

Where Vfb_nom is 495mV (min) 500mV (typ) 505mV (max).

No, this won't go in the datasheet because these values have been measured in a specific environment and vary from application to application. I am offering them as guidance in your design; not as hard set parameters.