24-V, 8-ch NMOS low-side driver with 5-V LDO and zero-Volt detect

The power supply provides regulated 5-V output to power the system microcontroller and drive eight low-side switches. The AC zero-detect circuitry is monitoring the crossover voltage of the mains AC supply. The resultant signal is a low-frequency clock output on the ZVS terminal, based on the AC-line cycle. This information allows the microcontroller to reduce in-rush current by powering loads on the AC-line peak voltage.

A serial communications interface controls the eight low-side outputs; each output has an internal snubber circuit to absorb the energy in the inductor at turn OFF. Alternatively, the system can use a fly-back diode to VIN to help recirculate the energy in an inductive load at turn OFF.