Hvic primary side power supply controller including

Abstract

A primary side power supply controller includes a full-bridge/half-bridge driver and is capable of being implemented on a single HVIC chip. Control circuitry enables operation in PWM, resonant, and phase-shift control modes. In the phase-shift control mode, a phase shift generator receives two input pulse train signals and generates two output pulse train signals, each having a 50% duty cycle, which are phase-shifted in a range from 0 to 180.degree. by an amount proportional to the duty cycle of the input pulse train signals and also proportional to the power supply load requirement. Dead time circuitry for ensuring that no two switching devices in a half-bridge, or in the same leg of a full-bridge, are conductive simultaneously employs a symmetrical delay circuit which independently delays the rising and falling edges of each signal pulse.