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PFCLLCSREVM034: To imrove Efficiency

Kento Sato
Intellectual 830 points
Part Number: PFCLLCSREVM034
Other Parts Discussed in Thread: UCC256403, UCC25640EVM-020,

Hi team,

Now customer evaluates UCC256403 with PFCLLCSREVM034 and UCC25640EVM-020.

With PFCLLCSREVM034, efficiency on 10% Load is around 80%, which is worse than UCC25640EVM-020.

Could you provide your tips to improve efficiency on PFCLLCSREVM034?

Regards,

Kento

  • 0
    TI__Genius 13245 points

    Hi Kento,

    You can increase the burst mode threshold inorder to reduce the switching losses at 10% load. That should further improve the efficiency.

    Regards

    Manikanta P

  • 0 in reply to Manikanta Pallantla
    TI__Intellectual 2550 points

    Hi Manikanta,

    Do you have guideline which option is the best for setting BMTL/BMTH(=option1, 2, 3, 4, 6) and BMTH value set by R1 and R2? My customer is changing the BMTL and BMHH value to maintain bust mode longer.

    I learned basic works of UCC256403 and could understand BMTL and BMTH is for bust mode entry and exit threshold. But I don't have much experience to touch LLC circuit

    Best regards,

    Shotaro

  • 0 in reply to Shotaro Sakai
    TI__Genius 13245 points

    Hi Shotaro,

    You can increase the BMTL threshold to prolong the burst off period. However, this would increase the ripple in the output voltage as the controller is not switching for a longer duration. In addition, you should ensure that the boost strap capacitor voltage does not drop below its threshold limit, as it requires frequent switching in order for it to be recharged. 

    Use the design calculator for finding LL/SS pin resistor values.

    Regards

    Manikanta P