ML4813

The ML4813 is a PWM controller designed for use in a discontinuous "flyback" or "buck-boost" type power factor correction (PFC) system for low power, low cost applications.

The circuit includes a precision reference, oscillator, error amplifier, over-voltage comparator, over-current comparator, and an extra op-amp as well as a high current output. In addition, start-up is simplified by an under-voltage lockout circuit.

In a typical application, the ML4813 functions as a voltage mode regulator. By maintaining a constant duty cycle, the current follows the input voltage, making the impedance of the entire circuit appear purely resistive. With the flyback circuit, power factors of 0.99 are easily achievable with a small output inductor and a minimum of external components.