LM5156: Crossover Frequency & FCO problem

Paul Chang

Prodigy 60 points

Part Number: LM5156

Tool/software:

Hi TI teams

I would like to ask what are the specifications for crossover frequency during design?
Should we exceed the FCO or not?

5 months ago

+1 Hassan Jamal 5 months ago

TI__Expert 4090 points

Hi Paul,

Thanks for using the E2E forum.

The Fco or Bandwidth should be

< 1/3 × Frhpz

< 1/10 × (1 − Dmax) × Fsw

The gain cross over frequency is also use to measure the phase margin. You need to adjust the Comp pin compensation network to have a Phase margin >60 degrees and a cross over frequency with in the above define limits.

Best Regards,

Hassan

0 Paul Chang 5 months ago in reply to Hassan Jamal

Prodigy 60 points

Hi Hassan

I have a problem
When I measured the Bode plot on the oscilloscope, it matched my calculations perfectly.
I would like to ask if there is a problem with my design?

the Bode plot on the oscilloscope