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UCC28086: ISET(RSET) calculation

Part Number: UCC28086

Dear Sir,

This is Vaibhav Kundariya from eInfochips an Arrow company.

we are working on UCC28086 based Push-pull SMPS. So can you please help us to calculate the RSET value for ISET pin of the UCC28086D controller?

As per the above image calculation 

VOSC peak =1.5V

RF = 1K

RAMP Voltage Height = ?

Can you please guide us on how to calculate RAMP VOLTAGE HEIGHT in the above equation for the UCC28086D controller? 

Thanks in advance


Vaibhav Kundariya

  • Hi

    ISET peak is listed in table on page 4, typical 30uA.

    Based on page 6, IRAMP = 5 x ISET = 150 uA, also see page 4

    RAMP Voltage Height is your design need for your current slope. I think you can start with 0.5 x Vcs = 0.5 x 0.52V = 0.26V, 0.52V is maximum Vcs based on page 4. Then you can get your initial RSET for your current slope compensation. RSET will need to tune up on bench work.