Natural Interleaving transition-mode PFC controller with improved audible noise immunity

Optimized for consumer applications concerned with audible noise elimination, this

solution extends the advantages of transition mode – high efficiency with low-cost

components – to higher power ratings than previously possible. By utilizing a Natural

Interleaving™ technique, both channels operate as masters (that is, there is

no slave channel) synchronized to the same frequency. This approach delivers

inherently strong matching, faster responses, and ensures that each channel operates

in transition mode.

Expanded system level protections feature input brownout and dropout recovery, output

over-voltage, open-loop, overload, soft-start, phase-fail detection, and thermal

shutdown. The additional FailSafe over-voltage protection (OVP) feature protects

against shorts to an intermediate voltage that, if undetected, could lead to

catastrophic device failure. Advanced non-linear gain results in rapid, yet smoother

response to line and load transient events. Reduced bias currents improve stand-by

power efficiency. Special line-dropout handling avoids significant current

disruption and minimizes audible-noise generation.