Hi:
Sorry need you guys help.
1. Could you provide Vout’s deviation in power save mode?
2. Do you have formula about estimating Vout range in power save mode?
3. Why Vout in save mode is a little higher than PWM mode's?
please see sheet2
2061.tps63020 issue.xls
thanks
The TPS6302x is expected to have a higher output voltage in power save (PFM) mode.
This prevents the output voltage from dipping below the set output when a load is applied.
In PFM mode, the feedback is between two points near .500V and .525V which is why the average output is measured at .512.
I have measured this on an evaluation module with no load to demonstrate. The results are visible in the following scope shot:
Though we don't have a formula for estimating Vout range in power save mode (PFM), I recommend designing for significant margin using 25mV as the range on Vfb for PFM.
The other possibility is to operate in PWM mode where Vfb is specified in the datasheet to be 495-505mV. This will however decrease your efficiency at loads less than approx. 100mA.
Daniel:
thanks for your detail explanation
do you have the presentation about this PFM principle?