You already provided link for current transformer. I am unable to identify suitable one.
Also you said that you will not be able to provide exact part no.
Could you give required specification and turn ratio of the current transformer required for below circuit ? CT1+ and CT2+ are from CT. Want to know how many turns are required in the secondary.
Hi Chandran,
Thank you for the query on UCC28070.
We have already discussed the detailed procedure for CT selection in our previous e2e threads mentioned below:
To summarize in brief, here are the steps to choose CTs for this application.
Choose Nct according the peak current for your application where Ipeak is the peak current as per your calculations and Irs is the current sense signal (usually around 100mA).
Selection of the current sense resistors (RSA and RSB ) is based on the peak current limit signal (VS ~3.7V) and the peak current on the secondary side of the current sense transformer. A factor of 0.9 was multiplied by the current sense signal to leave room for the 10% PWM ramp that is used to make this design more noise immune at lighter loads.
The magnetizing inductance (LM) of the current sense transformer should be selected or designed so the magnetizing current is less than 2% of the maximum current sense signal.
Above equations should help designing the current transformer.
Regards,
Harish
