Abstract: A method and circuit for controlling the delivery of power having a current component to a load having an inductive component, the method comprising selectively switching power to the load with a switch, wherein the switch is caused to operate at the threshold of saturation during a conduction state such that the switch self commutates to its off state when the magnitude of the current through the load is substantially zero. The method and circuit may be used in a number of applications for detecting a current zero crossing and may be applied to circuits such as dimmer circuits.

Abstract: Disclosed is an inductive load detection circuit for detecting the presence of an inductive load on a dimmer circuit. The detection circuit provides for enhanced detection of the inductive load by detecting voltage ringing resulting from a turn-off of a switching element in the circuit. The ringing can be enhanced by providing a faster turn-off rate in an initial period than a turn-off rate in a steady state period. Also disclosed is a dimmer circuit comprising the inductive load detection circuit.

Abstract: Disclosed is a method and apparatus for detecting an overcurrent condition in a dimmer circuit having two switches, each for controlling power delivered to a load, each switch having a respective anti-parallel diode. The method comprises sensing a voltage drop across one of the anti-parallel diodes, comparing the sensed voltage drop with a reference voltage, and determining that an overcurrent condition exists if the sensed voltage drop exceeds the reference voltage. Also disclosed is a dimmer circuit embodying the method.

Abstract: Disclosed is an overcurrent protection circuit for use in a dimmer circuit having a switching device for controlling power delivered to a load. The overcurrent protection circuit comprises means for sensing a load current passing through the load and means for comparing the sensed load current with a threshold, wherein the threshold is a dynamic current threshold. Also disclosed is a dimmer circuit comprising the overcurrent protection circuit.

Abstract: Disclosed is a circuit for detecting the presence of an inductive load. The circuit uses a voltage ringing detector to detect a voltage ringing signal across the inductive load and a signal generator for generating a signal indicating the presence of the inductive load upon detection of the ringing signal. The circuit may be used in a dimmer circuit for controlling the load. The circuit may be used as a load detector for a universal dimmer or may be used in a protection circuit for circuits not designed to control inductive loads.

Abstract: Disclosed is an inductive load detection circuit for detecting the presence of an inductive load on a dimmer circuit. The detection circuit provides for enhanced detection of the inductive load by detecting voltage ringing resulting from a turn-off of a switching element in the circuit. The ringing can be enhanced by providing a faster turn-off rate in an initial period than a turn-off rate in a steady state period. Also disclosed is a dimmer circuit comprising the inductive load detection circuit.

Abstract: Disclosed is a method and apparatus for detecting an overcurrent condition in a dimmer circuit having two switches, each for controlling power delivered to a load, each switch having a respective anti-parallel diode. The method comprises sensing a voltage drop across one of the anti-parallel diodes, comparing the sensed voltage drop with a reference voltage, and determining that an overcurrent condition exists if the sensed voltage drop exceeds the reference voltage. Also disclosed is a dimmer circuit embodying the method.

Abstract: Disclosed is an overcurrent protection circuit for use in a dimmer circuit having a switching device for controlling power delivered to a load. The overcurrent protection circuit comprises means for sensing a load current passing through the load and means for comparing the sensed load current with a threshold, wherein the threshold is a dynamic current threshold. Also disclosed is a dimmer circuit comprising the overcurrent protection circuit.

Abstract: A method and circuit for controlling the delivery of power having a current component to a load having an inductive component, the method comprising selectively switching power to the load with a switch, wherein the switch is caused to operate at the threshold of saturation during a conduction state such that the switch self commutates to its off state when the magnitude of the current through the load is substantially zero. The method and circuit may be used in a number of applications for detecting a current zero crossing and may be applied to circuits such as dimmer circuits.

Abstract: Disclosed is a universal dimmer which detects the type of load it is connected to each time the universal dimmer is activated. Information relating to the type of load connected to the universal dimmer is therefore not required to be stored for future use. In one form, the universal dimmer begins each operation in the trailing edge mode and upon detection of an inductive load, switches to leading edge mode.

Abstract: Disclosed is a circuit for detecting the presence of an inductive load. The circuit uses a voltage ringing detector to detect a voltage ringing signal across the inductive load and a signal generator for generating a signal indicating the presence of the inductive load upon detection of the ringing signal. The circuit may be used in a dimmer circuit for controlling the load. The circuit may be used as a load detector for a universal dimmer or may be used in a protection circuit for circuits not designed to control inductive loads.

Abstract: A dimmer circuit arrangement is disclosed including a second control circuit for controlling the operation of a triac for delivering current to a load, and a first control circuit for controlling the operation of an IGBT power semiconductor switch for controlling the rate of rise of load voltage. The first control circuit also controls the operation of the second control circuit.

Abstract: A dimmer circuit arrangement is disclosed including a second control circuit (40) for controlling the operation of a triac (50) for delivering current to a load (60), and a first control circuit (10) for controlling the operation of an IGBT power semiconductor switch (20) for controlling the rate of rise of load voltage. The first control circuit also controls the operation of the second control circuit.