GENERAL DESCRIPTION

The CM6800A is a controller for power factor corrected, switched mode power suppliers. 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 compiles with

IEC-1000-3-2 specifications. Intended as a BiCMOS version of the industry-standard ML4824, CM6800A includes circuits for the implementation of leading edge, average current, “boost” type power factor correction and a trailing edge, pulse width modulator (PWM). Gate-driver with 1A capabilities minimizes the need for external driver circuits. Low power requirements improve efficiency and reduce component costs.

FEATURES

Pin to pin compatible with ML4800 and FAN4800

Additional folded-back current limit for PWM section.

23V Bi-CMOS process

VIN OK turn on PWM at 2.25V instead of 1.5V(ML4800).

Internally synchronized leading edge PFC and trailing edge PWM in one IC

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

Low start-up current (100μA typ.)

Low operating current (3.0mA type.)

Low total harmonic distortion, high PF

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

Average current, continuous or discontinuous boost leading edge PFC

VCC OVP Comparator, Low Power Detect Comparator

PWM configurable for current mode or voltage mode operation

Current fed gain modulator for improved noise immunity

Brown-out control, over-voltage protection, UVLO, and soft start, and Reference OK