Average current PFC controller for industrial power supplies
The Texas Instruments UCC2818D is an average current mode power factor correction (PFC) controller designed for boost converters requiring near-unity power factor and low THD. It operates over a 12V to 17V supply range with a 150 µA startup current, making it efficient for bias supply designs in off-line power supplies.
The 6kHz to 220kHz switching range is wide enough to avoid AM radio bands and to optimize the boost inductor for size versus core loss. At the low end, 6kHz allows very small ferrite cores but large winding turns; at 220kHz the inductor shrinks but core losses and gate-drive losses climb. Most designs settle between 50kHz and 100kHz for a practical balance. The frequency is set with a single resistor on the RT pin, so last-minute tweaks are straightforward.