Power factor and PWM controller TDA 16888

Abstract

TDA 16888 is designed for off-line switched mode power supplies (SMPS) with optional universal input and power factor correction, for example, for PCs, monitors, CTVs and industrial applications. Combi-IC TDA 16888 includes the pulse width modulated (PWM) control for a SMPS and the control for the preconverter to improve the power factor and to reduce the harmonics of the AC input current. Both sections are internally synchronized on the same operating frequency. The preferred topology of the PFC-preconverter is boost, but flyback is also possible. The PWM section can be designed as a forward or as a flyback converter. Maximum duty cycle of the PFC is about 95%, in order to achieve minimal line current gaps. Maximum duty cycle of the PWM is limited to 50% to prevent transformer saturation. In normal operation the PFC section operates with dual loop control. A first control loop controls the shape of the line current by average current control enabling either continuous or discontinuous operation mode. The second loop controls the DC bus voltage. There is a third control loop available that enables the PFC section as an auxiliary power supply even during disabling the PWM section. In this paper the PFC preconverter, PWM converter, PFC and PWM gate drive, and oscillator and synchronisation are described.