FAN9612

The FAN9612 interleaved dual Boundary-Conduction-Mode (BCM) Power-Factor-Correction (PFC) controller operates two parallel-connected boost power trains 180? out of phase. Interleaving extends the maximum practical power level of the control technique from about 300W to greater than 800W. Unlike the continuous conduction mode (CCM) technique often used at higher power levels, BCM offers inherent zero-current switching of the boost diodes (no reverse-recovery losses), which permits the use of less expensive diodes without sacrificing efficiency. Furthermore, the input and output filters can be smaller due to ripple current cancellation and effective doubling of the switching frequency.

The FAN9612 converters operate with variable frequency, which is a function of the load and the instantaneous input / output voltages. The switching frequency is limited between 18kHz and 600kHz. The Pulse Width Modulators (PWM) implement voltage-mode control with input voltage feedforward. When configured for PFC applications, the slow voltage regulation loop results in constant on-time operation within a line cycle. This PWM method, combined with the BCM operation of the boost converters, provides automatic power factor correction.

The FAN9612 offers bias UVLO, input brownout, input over-voltage, over-current, open-feedback, over-temperature, output over-voltage, and redundant latching over-voltage protections. Furthermore, the converters? output power is limited independently of the input RMS voltage. Synchronization between the power stages is maintained under all operating conditions.