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 IEC-1000-3-2 specifications. Intended as a BiCMOS 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 Modulator (PWM). 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 short-circuit protection.

• Low start-up current(100µA typical)
• Low operating current(2.5mA typical)
• Low total harmonic distortion, high power factor
• Pin-compatible upgrade for the ML4800
• Average current, continuous, or discontinuous boost leading-edge PFC
• Slew rate enhanced transconductance error amplifier for ultra-fast PFC response
• Internally synchronized leading edge PFC and trailing edge PWM
• Reduction of ripple current in the storage capacitor between the PFC and PWM sections
• PWM configurable for current-mode or voltage-mode operation
• Additional folded-back current limit for PWM section
• 20V BiCMOS process
• V_IN OK guaranteed turn-on PWM at 2.25V
• V_CC OVP comparator, low-power detect comparator
• Current-fed gain modulator for improved noise immunity
• Brownout control, over-voltage protection, UVLO, soft-start, and reference OK
• Available in 16-DIP and 16-SOIC (wide) packages

• Desktop PC Power Supply
• Internet Server Power Supply
• Uninterruptible Power Supply (UPS)
• Battery Charger
• DC Motor Power Supply
• Monitor Power Supply
• Telecom System Power Supply
• Distributed Power