High resolution digital diode emulator for DC-DC converters

A digital diode emulator for a DC-DC voltage converter having a controller, which generates a switching signal that switchably controls operation of a switching circuit containing first and second electronic power switching devices coupled between respective power supply terminals, a common node thereof being coupled through an inductor element to an output voltage terminal and a capacitor, said digital diode emulator comprising:

• a switch-off signal control circuit, which is operative to generate a turn-off signal for turning off said second electronic power switching device;
• a turn-off signal controller, which is operative, over successive cycles of said switching signal, to adjust the turn-off time of said switch-off signal based upon respective contents of a digital counter, the contents of which are successively modified by a clock signal having a frequency in excess of said switching signal, and in accordance with successively sensed digital states of said voltage at said common node.

In a diode emulator for a DC-DC voltage converter, having a controller which generates a switching signal, that switchably controls operation of a switching circuit, containing first and second electronic power switching devices coupled between respective power supply terminals, and having a common node thereof coupled through an inductor element to an output voltage terminal and a capacitor element, the improvement wherein said diode emulator includes:

• a digital counter which, for each switching signal cycle, counts clock signals having a frequency higher than that of said switching signal between turn-on and turn-off of one of said first and second electronic power switching devices, and wherein, over successive switching signal cycles, contents of said digital counter are used to effectively ‘dither’ the turn-off time of said one of said first and second electronic power switching devices about the zero-crossing point of current through said inductor current.