General purpose MCU timers and isolated gate drivers

In this work, we show some techniques to generate complex gate driver signals for switching converters isolated by pulse transformer when using simple timers available in low cost microcontrollers. Two approaches are presented in order to overcome the drawbacks (due to volts-second parameter), when driving a power MOSFET or IGBT with pulses having very low or very high duty-cycle values. The first with one up-down timer and the second, using two up counting timers. Both of which, providing PWM outputs to drive high voltage AC loads. Proper gate drive circuits are proposed. Experimental results and comparison with others existing techniques are provided as well.