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UCC28180: Can the chip achieve a power factor (PF) of not less than 99% for power levels above 120W, and a PF of not less than 90% for power levels below 120W?

WU QINGLONG
Prodigy 10 points
Part Number: UCC28180

Tool/software:

We need to realize the power more than 120W PF value not less than 99%, power less than 120W PF not less than 90%, the maximum power of 250W, UCC281180DR this chip can be realized? According to the 350W circuit design recommended by the document, the PF value can only reach about 90%. Our schematic diagram is as follows. Is there any recommended design that meets our requirements?

  • 0
    TI__Mastermind 31180 points

    Hello Qinglong, 

    Part of your requirements for performance ("...and a PF of not less than 90% for power levels below 120W..") is not possible to achieve with ANY PFC controller, if this power level range extends down to 0W.  There will be some power level where the X-capacitors in the EMI line filter will shift the current-to-voltage phase angle enough to make cosθ <0.90.   
    This power level will be higher at high line than it will be at low line. 

    The UCC28180 EVM User Guide ( https://www.ti.com/lit/pdf/sluuat3 ) Figure 4 shows very high PF results for low-line operation (85-120Vac) but not as good at high-line.
    Part of the reduction of PF at high-line is due to X-caps.  Your EMI filter can be redesigned to minimize their effect.

    Please provide complete input and output specifications. 
    Your schematic diagram shows the PFC output node labeled as "310V", but the feedback divider network programs Vout for 382V.  This is confusing. 
    If you are running at low-line only, it may be possible to meet your first requirement of PF > 0.99 for loads > 120W (50% of full-load 240W). 

    Regards,
    Ulrich