GENERAL DESCRIPTION

The ML4804 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 IEC1000-3-2 specification. Intended as a BiCMOS enhancement of the industry-standard ML4824, the ML4804 includes circuits for the implementation of leading edge, average current, “boost” type power factor correction and a trailing edge, pulse width modulator (PWM). It also includes a TriFault Detect™ function to help ensure that no unsafe conditions will result from single component failure in the PFC. 1A gate-drive outputs minimize the need for external driver circuits. Low power requirements improve efficiency and reduce component costs.

FEATURES

■ Internally synchronized leading-edge modulated PFC and trailing-edge modulated PWM in one IC

■ TriFault DetectTM for UL1950 compliance and enhanced safety

■ VCCOVP provides additonal PFC fault protection

■ Slew rate enhanced transconductance error amplifier for ultra-fast PFC response

■ Low power: 200µA startup current, 5.5mA operating current

■ Low total harmonic distortion, high PF

■ Reduces ripple current in the storage capacitor between the PFC and PWM sections

■ Average current, continuous boost leading edge PFC

■ PWM configurable for current-mode or voltage mode operation

■ Overvoltage and brown-out protection, UVLO, and soft start