Phase cut dimming control and protection

A switch, comprising:

• a first MOSFET and a second MOSFET connected in anti-series;
• the two source terminals of the MOSFETs being connected together to form a common source terminal and the two gate terminals of the MOSFETs being connected together to form a common gate terminal to receive a switch control signal;
• and
• a differential amplifier comprising a non-inverting input terminal, an inverting input terminal and an output terminal;
• wherein:
• the negative voltage at the drain terminals of the MOSFETs is coupled to the non-inverting input terminal;
• the positive voltage at the drain terminals of the MOSFETs is coupled to the inverting input terminal;
• the common gate terminals of the MOSFETs is coupled to the output terminal of the amplifier;
• in the event of over-current state of the switch, the negative voltage at the non-inverting input terminal drives the amplifier to turn off the switch control signal;
• in the event of over-temperature state of the switch, the positive voltage at the inverting input terminal drives the amplifier to turn off the switch control signal;
• whereby once the switch is turned off it is locked off until the end of the half cycle of the AC voltage.

A method of phase cut dimming to control the amount of power delivered from an AC power source to a load, comprising:

• turning on and turning off the current from the power source to the load by a switch;
• converting the AC voltage from the power source by rectification to a pulsating DC voltage which is coupled to the switch;
• detecting zero crossing points of the AC voltage through the pulsating DC voltage with a bleeder with a controllable impedance coupled to the output of the rectifier;
• and
• controlling the switch in synchronization with the zero crossing by an adjustable timer.

A method of switching, comprising:

• connecting a first MOSFET and a second MOSFET in anti-series;
• the two source terminals of the MOSFETs being connected together to form a common source terminal and the two gate terminals of the MOSFETs being connected together to form a common gate terminal to receive a switch control signal;
• coupling the switch to a differential amplifier comprising a non-inverting input terminal, an inverting input terminal and an output terminal, wherein:
• the negative voltage at the drain terminals of the MOSFETs is coupled to the non-inverting input terminal;
• the positive voltage at the drain terminals of the MOSFETs is coupled to the inverting input terminal of the amplifier;
• the common gate terminals of the MOSFETs is coupled to the output terminal of the amplifier;
• in the event of over-current state of the switch and by the negative voltage at the non-inverting input terminal, driving the amplifier to turn off the switch control signal;
• in the event of over-temperature state of the switch and by the positive voltage at the inverting input terminal, driving the amplifier to turn off the switch control signal;
• whereby once the switch is turned off, it is locked off until the end of the half cycle of the AC voltage.