PFC controller for CCM boost stages
The Texas Instruments UCC29950D is a power factor correction (PFC) controller operating in Continuous Conduction Mode (CCM), designed for boost-type PFC stages in AC-DC power supplies. It switches between 87kHz and 109kHz, suiting magnetic component sizing for designs from a few hundred watts up to several kilowatts. The wide supply range of 11V to 18V lets it run off a simple auxiliary winding or bias regulator, and the -40°C to 125°C operating temperature range covers industrial and outdoor telecom environments where the PFC stage sees elevated ambient temperatures.
Switching frequency and magnetic sizing
The 87kHz to 109kHz switching range is typical for CCM PFC controllers — fast enough to keep the boost inductor small, but not so high that gate-drive losses or switching losses dominate. At 100kHz, a 400W PFC stage with a 400V output bus needs roughly a 400µH to 600µH inductor; the controller's internal oscillator tolerance (±11% around the center frequency) is tight enough to avoid saturating the core across temperature. If you are targeting a specific EMI frequency band, the 87kHz lower edge helps keep the fundamental below 150kHz for CISPR 22 Class B conducted emissions compliance.
Temperature grade and deployment environment
Rated for -40°C to 125°C, this part is specified for industrial and automotive-adjacent applications where the PFC controller sits on a hot power board — think motor drives, battery chargers, server PSUs, or outdoor LED drivers. The 125°C junction temperature allows the controller to share a heatsink or be placed near the boost MOSFET and diode without derating the bias supply. No AEC-Q100 qualification is listed, so for under-hood automotive designs you would need to check the TI qualification status separately.
Active lifecycle — no LTB risk
ROHS3 compliant per the listing.