Buck converter with averaged feedback

[francis29]

Hi,
We working on power supply design and we are referring to the reference design from Texas Instruments.
The feedback pin will only senses the output voltage during the OFF time of the Q1 MOSFET ( since D2 will block the negative voltage ).
What is the type of feedback used here?
How to assess the closed loop stability here?

 

[cupoftea]

To assess stability just scope vout. Also check the switching node voltage to check your pulses are nice and clean train of pulses.
You have C2 there, which is refreshed every switching cycle, so it is feedback just like other....so its almost as if you are regulating the actual outut anyway.......if you want you can place another R between divider and FB pin, and put an RC across that, to give you more options.

I am not sure why you use such small C7 (220pf)....as your duty cycle only needs to be very low.