FAN4800

The FAN4800 is a controller for power factor corrected, switched mode power supplies. Power Factor Correction (PFC) allows the use of smaller, lower cost bulk capacitors, reduces power line loading and stress on the switching FETs, and results in a power supply that fully complies with the IEC-1000-3-2 specifications. Intended as a Bi-CMOS version of the industry-standard ML4800, the FAN4800 includes circuits for the implementation of leading edge, average current, boost type power factor correction and a trailing edge, pulse width PWM (Pulse Width Modulator). A gate driver with 1A capabilities minimizes the need for external driver circuits. Low power requirements improve efficiency and reduce component costs.

An over voltage comparator shuts down the PFC section in the event of a sudden decrease in load. The PFC section also includes peak current limiting and input voltage brownout protection. The PWM section can be operated in current or voltage mode, at up to 250kHz, and includes an accurate 50% duty cycle limit to prevent transformer saturation.

The FAN4800 includes a folded-back current limit for the PWM section to provide a short circuit protection function.