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Original question:

UCC25800-Q1: questions about B version& Non-B version and OCP setting

UCC25800-Q1: Need clarity in OCP1 settings in UCC25800-Q1

jesica N
Prodigy 40 points
Part Number: UCC25800-Q1
Other Parts Discussed in Thread: UCC25800

Tool/software:

Hello,

I am using UCC25800-Q1 as a part of my design for LLC resonant converter. I am using 18K and 15K with tolerance 2.5%. The OCP1 threshold setting depends on this resistor. The min and max Rth as per this design is 

Ra = 18K*wc(0.025) = 17.55K to 18.45K ohms

Rb = 15K*wc(0.025)=  14.625K to 15.375K ohms

Rthmin = 7.97K ohms

Rthmax= 8.38K ohms.

The above setting as not matching the range given in data sheet. OCP1_4. 

  • +1
    TI__Mastermind 25755 points

    Jesica,

    Please make sure you are not using the UCC25800B-Q1 version which does not have OCP1 setting available but does follow OCP2 threshold settings shown in Table 8-1. You cannot achieve OCP1 thresholds if you are using UCC25800B-Q1. If you are using the UCC25800-Q1 (non-B) version and believe the OCP1_4 threshold settings are not correct, please provide waveforms or explain how you come to the conclusion that Ra=18k and Rb=15k are not setting the correct OCP1_4? I would also recommend to use better tolerance resistors than 2.5%. Recommend no less than 1% and prefer 0.1%.

    Regards,

    Steve