A trickle power supply for a light switch module according to the invention enables power to an electronic circuit to be taken directly off the hot line. The power supply operates under what is referred to as the "switched leg theory". All power is taken off the standard switched leg of the light circuit. The power supply bleeds enough current to power its electronic circuitry without turning on the load device, i.e., the light. At the same time, the maximum current to the load is limited to prevent shorting out of the power supply which would effectively disable the switch module.
A circuit is provided for supplying a load from an AC voltage supply. The circuit includes a control circuit and a bidirectional switch coupled in series with the load. The bidirectional switch includes two one-way switches connected in antiparallel, and the control circuit controls the bidirectional switch based on a relatively low DC voltage. The bidirectional switch is connected to a first terminal of the AC voltage supply, and the DC voltage is referenced to the first terminal of the AC voltage supply. Additionally, an apparatus connected to an AC voltage supply and a relatively low DC voltage is provided. The apparatus includes a control circuit, a load to be supplied by the AC voltage supply, and a bidirectional switch coupled in series with the load. The bidirectional switch includes two one-way switches connected in antiparallel, and the control circuit controls the bidirectional switch based on the DC voltage. The bidirectional switch is connected to a first terminal of the AC voltage supply, and the DC voltage is referenced to the first terminal of the AC voltage supply. In one preferred embodiment, each of the two one-way switches includes a MOS transistor coupled in series with a diode.
