The TDA 4862 is excellent convenient for designing a preconverter in ballasts and switched mode power supplies with sinusoidal line current consumption and a power factor approaching unity. The TDA 4862 controls a boost converter as an active harmonics filter in a discontinuous mode (free oscillating triangular shaped current mode). The TDA 4862 comprises an internal start-up timer, a high gain voltage amplifier, an one quadrant multiplier for approaching unity power factor, a zero current detector, PWM and logic circuitry, and totem pole MOSFET gate driver.