April 1998
ML4812 Power Factor Controller
GENERAL DESCRIPTION
The ML4812 is designed to optimally facilitate a peak current control boost type power factor correction system.
Special care has been taken in the design of the ML4812 to increase system noise immunity.
The circuit includes a precision reference, gain modulator, error amplifier, overvoltage protection, ramp compensation, as well as a high current output.
In addition, start-up is simplified by an under-voltage lockout circuit with 6V hysteresis.
In a typical application, the ML4812 functions as a current mode
regulator.
The current which is necessary to terminate the cycle is a product of the sinusoidal line voltage times the out...