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PMP9087: Reference Design formulas and rationales for buck usage of ucc28730

Luca Vola Gera
Prodigy 75 points

Part Number: PMP9087

Hello,

we are interest in design an high voltage to low voltage non isolated buck converter. We found the PMP9087 reference design that meets our requirements but on the ucc28730 there are no design equation for buck mode of usage

Is possible to have some explanation and formulas to set the reference output voltage and to design the values of componentes strictly related to the UCC28730.

Thank you,

best regards.

 

  • 0
    TI__Genius 9710 points

    Dear Gera,

    Thanks for interested in TI's products.

    I use the PMP9087's design as an example.

    To design the output voltage, you can follow the equation in UCC28710, as below:

    Use different R3 to design your output voltage:

    If you want to modify output to 5V, just change the 12==>5 in the equation below

    I hope the information here help you to design your circuit.

    Or you can provide more design information of your circuit.

    I can search is there design circuit suitable for you.

    Vin, Iin, Vo, Io, Fsw and so on.

    Best Regards

    Kevin

  • 0 in reply to Kuan Wei Chen (Kevin Chen)
    Prodigy 75 points
    Hello Kwen,
    thank you for the answer, in this way I can set the voltage reference (22V), my last question are:
    1) Which is the equation to calculate the R1 (38k3) value? i have tried with the formula for Rs1 in ucc28710 datasheet with Npa = 1 but I do not obtain the the 38k3 value.
    2) The capacitor C2 has only filtering purpose or is related to stability?
    Thank you in advance,
    best regards,
    Luca
  • 0 in reply to Luca Vola Gera
    TI__Genius 9710 points

    Dear Luca,

    The R1+R2 will be the total RS1, the Npa=1 is correct.

    The C2 here is for filtering.

    Best Regards

    Kevin