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UCC25600 for an AC/DC 24V power supply

Jean-Paul Busson
Intellectual 2715 points
Other Parts Discussed in Thread: UCC25600

Hello

Socomec, one of my customer is working on Electrricity Circuit breaker and will use a motor to control this equipment.

Input voltage is single phase 300 to 570Vac (400 to  820V DC) to generate a 24V isolated 400 to 600W.

They are looking the UCC25600.

They have already posted a E2E ads "Question on UCC25600 and SLOU293C: 600W isolated PFC power supply..."

Is the UCC25600 the best part to suggest? 

One of the point of interest for  Socomec is they  do NOT prefer to use frequency above 150kHz but need to have for so low frequency Burst mode.

It seems that if they limit the switching frequency at as exemple 100kHz but external resistor RT modulation, in such case if Vin increases then we can have no output regulation. Solution can be to have Burst mode but normally not at such low frequency.

Question is How to have working conditions including Burst mode with frequency lower than 150kHz?

Thanks to let me know or suggest another solution.

Thanks for your help and best regards

Jean-Paul

 

  • 0
    TI__Expert 3095 points

    Hi Jean-Paul,

    An application with such a wide input voltage range may not be a very good fit for the LLC power topology. The LLC converter is more often used after a PFC stage in which case the input voltage range is reduced.

    I passed your question to the UCC25600 designer and this was his response:

    "You can have the resistor limit the frequency to 100kHz by the resistor and then short the RT pin to ground to force it into burst in no time. This way, you can disable the IC without the soft start. I am not sure how they can get that burst signal. I guess that is the more difficult part."

    Hope this answers your question.

    Joe Leisten