Buck converter calculation does not match with LTspice results

[crutschow]

I was probing at different place sorry my mistake

So everything looks ok now?

Note that the high frequency oscillations you are seeing at the output of the switch is due to the stray inductance and capacitance in the circuit.
A RC snubber to critically damp the circuit can eliminate them if desired (try 150Ω and 50nF in series from each switch output to ground).

 

[Krishna Sankhyan]

Probably due to non-ideal parts
Check ESR, inductor DCR, diode/MOSFET drops, and CCM vs DCM.

 

[WHONOES]

A useful document that I have used in the past is "Buck-Converter Design Demystified" written by Donald Schelle and Jorge Castorena of Maxi Integrated Products.

You should be able to find it via "ElectronicDesign" web site using the below link.

Donald Schelle and Jorge Castorena, Technical Staff, Maxim Integrated Products, Sunnyvale, Calif.

www.electronicdesign.com

 

[WHONOES]

You may need to add a small amount of resistance in series with you inductor otherwise the simulator will regard it as a perfect inductor with an infinite Q with attendant simulation issues. 100 milli Ohm would be a good place to start.