Overview The ML4824 is a power correction factor controller for switching power supplies. Power Factor Correction (PFC) allows the use of small, lower cost large capacitors, reduces power line loads and stress on switching FETs, and results in full compliance with IEC1000-2-3 specifications in the power supply. The ML4824 circuit is included for implementing leading edge, average current, "boost" type power factor correction and trailing edge, pulse width modulation (PWM). The device is available in two versions; the ML4824-1 (fPWM=fPFC) and the ML4824-2 (fPWM=2×fPFC). Doubling the PWM switching frequency allows the user to design smaller output components while maintaining the optimum PFC operating frequency. An overvoltage comparator shuts down the PFC section in the event of a sudden load reduction. Part of the PFC also includes peak current limit and input voltage undervoltage protection. The PWM part can operate in current or voltage mode at up to 250kHz and includes a duty cycle limit to prevent transformer saturation.

Features in an internal synchronous PFC and PWM integrated circuit Low total harmonic distortion Reduced ripple current Capacitor average current between PFC and PWM sections in storage, PFC boost Fast transconductance amplifier voltage loop error high Efficient trailing edge PWM can be configured for current mode or voltage mode operation Average line voltage compensation and power saving control
The PFC's overvoltage comparator eliminates output "runaway" due to the load shedding rate currently fed to improve noise immunity Gain modulator overvoltage protection, UVLO and soft-start...