A lamp driver delivers an output voltage and output current to a lamp load. A current regulating circuit at a secondary side provides a feedback signal for use by the driver when in a current regulation mode. An overvoltage protection circuit detects an overvoltage condition of an output voltage and modulates the feedback signal during detection of the overvoltage condition. The overvoltage condition can then be recognized more easily based on the resulting modulation of the output voltage.

A lamp driver delivers an output voltage and output current to a lamp load. A current regulating circuit at a secondary side provides a feedback signal for use by the driver when in a current regulation mode. An overvoltage protection circuit detects an overvoltage condition of an output voltage and modulates the feedback signal during detection of the overvoltage condition. The overvoltage condition can then be recognized more easily based on the resulting modulation of the output voltage.

A controller for a power converter. The power converter comprises an inverter for receiving a supply power and providing an inverter output at an inverter frequency. There is a primary inductance for receiving the inverter output and providing a primary output. There is at least one current sensor for sensing at least one output current and providing at least one output current signal based on the at least one output current. The controller is adapted to receive the at least one output current signal, and control the inverter frequency by providing a switch control signal to the inverter based on the at least one output current signal and a reference signal thereby providing a desired primary output corresponding to the reference signal.

A controller for a power converter. The power converter comprises an inverter for receiving a supply power and providing an inverter output at an inverter frequency. There is a primary inductance for receiving the inverter output and providing a primary output. There is at least one current sensor for sensing at least one output current and providing at least one output current signal based on the at least one output current. The controller is adapted to receive the at least one output current signal, and control the inverter frequency by providing a switch control signal to the inverter based on the at least one output current signal and a reference signal thereby providing a desired primary output corresponding to the reference signal.

Fault-protection is provided in electrical devices by redundancy in diodes on diode legs of the bridge rectifier and a fault-protection circuit. The fault-protection circuit is configured: (i) for electrical coupling between a return of input DC power to a step-down switching DC-DC converter and a return rail of rectified DC voltage of the output DC power generated by the bridge rectifier, and is configured to perform opening the switch based on sensing a current fault or voltage fault, or (ii) to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

Fault-protection is provided in electrical devices by redundancy in diodes on diode legs of the bridge rectifier and a fault-protection circuit. The fault-protection circuit is configured: (i) for electrical coupling between a return of input DC power to a step-down switching DC-DC converter and a return rail of rectified DC voltage of the output DC power generated by the bridge rectifier, and is configured to perform opening the switch based on sensing a current fault or voltage fault, or (ii) to sense current from a step-down switching DC-DC converter, a first voltage from the step-down switching DC-DC converter, and/or a second voltage at an output of the step-down switching DC-DC converter, and open the circuit on a fault.

A minimum voltage detector circuit is disclosed. The circuit includes a plurality of LED strings each having a plurality of series-coupled LEDs. The minimum voltage detector circuit is configured to detect a minimum voltage from among the plurality of LED strings, and also to perform open/short detection among the plurality of LED strings. The minimum voltage detector circuit includes a plurality of voltage comparators and correspondingly coupled replica circuits. Each of the voltage comparators includes an amplifier having a first input coupled to a cathode of a last LED of one of the plurality of LED strings, an output, and a second input coupled to the output. Each voltage comparator further includes a replica circuit coupled to the amplifier. The replica circuit is configured to maintain an output transistor of the amplifier in an active state when the amplifier is in an unbalanced state.

A load control device for controlling the intensity of a lighting load, such as a light-emitting diode (LED) light source, may include a power converter circuit operable to receive a rectified AC voltage and to generate a DC bus voltage, a load regulation circuit operable to receive the bus voltage and to control the magnitude of a load current conducted through the lighting load, and a control circuit operatively coupled to the load regulation circuit for pulse width modulating or pulse frequency modulating the load current to control the intensity of the lighting load to a target intensity. The control circuit may control the intensity of the lighting load by pulse width modulating the load current when the target intensity is above a predetermined threshold and control the intensity of the lighting load by pulse frequency modulating the load current when the target intensity is below the predetermined threshold.

A voltage-regulating drive circuit for an LED luminaire is disclosed. The drive circuit includes one or several series of LED light engines. A voltage source with a regulator is connected to the series of LED light engines to forward-bias the light engines. The circuit also includes a driver integrated circuit, which may drive the series of LED light engines using, e.g., pulse-width modulation (PWM). The circuit also includes a feedback circuit connected to the cathode end of the series of LED light engines. The feedback circuit receives a remainder voltage and creates a feedback output signal that upregulates or downregulates the regulator of the voltage source to keep a minimum operating voltage on the driver integrated circuit and to compensate for variations in forward voltages among LED light engines in the series.

A voltage-regulating drive circuit for an LED luminaire is disclosed. The drive circuit includes one or several series of LED light engines. A voltage source with a regulator is connected to the series of LED light engines to forward-bias the light engines. The circuit also includes a driver integrated circuit, which may drive the series of LED light engines using, e.g., pulse-width modulation (PWM). The circuit also includes a feedback circuit connected to the cathode end of the series of LED light engines. The feedback circuit receives a remainder voltage and creates a feedback output signal that upregulates or downregulates the regulator of the voltage source to keep a minimum operating voltage on the driver integrated circuit and to compensate for variations in forward voltages among LED light engines in the series.