An apparatus for driving LEDs using high voltage includes two LED driving circuits and two switches that can be turned on or off by a universal controller so as to connect the two LED driving circuits in two different configurations. When the input voltage is in a range from rectified 90 volt AC to rectified 140 volt AC, the two switches are controlled in such a way that the two LED driving circuits are connected in parallel. When the input voltage V.sub.IN is in a range from rectified 180 volt AC to rectified 265 volt AC, the two switches are controlled to connect the LED segments of the LED unit in one LED driving circuit in series with the other LED driving circuit.

A power supply system includes a converter configured to generate a drive signal based on a rectified input signal for powering a light source, a ripple control system including a voltage-controlled resistor (VCR) coupled to a secondary-side of the converter and configured to dynamically adjust a resistance of the VCR to compensate for ripples in the drive signal, and a controller configured to sense an output voltage of the converter, to calculate a voltage drop across the VCR, and to generate a feedback signal to control the drive signal of the converter based on the sensed output voltage and the calculated voltage drop.

An LED driver IC for driving external strings of LEDs includes a prefix register and a data register connected in series with each other and with the prefix and data registers in other driver ICs. The prefix and data registers of the driver ICs are connected in a daisy chain arrangement with an interface IC. The interface IC loads data identifying a functional latch into the prefix register and data defining a functional condition into the data register of each driver IC. The data in the data register is then transferred to the functional latch to control the functional condition within the LED driver IC.

Methods for controlling power consumption and temperature in an LED luminaire are disclosed. The LED luminaire has one or more sets of LED light engines disposed on a printed circuit board (PCB), some or all of which are activated in response to an instruction or set of instructions. The instruction or set of instructions are processed to derive an indication of power consumption for each of the one or more sets of LED light engines. Power allocations for the one or more sets of LED light engines are adjusted to meet targets. This can be done by, e.g., ramping up or down the duty cycle of active sets of LED light engines by a uniform factor until the targets are met. Temperature control methods similarly ramp down the duty cycle of active sets of LED light engines uniformly over time if the measured temperature of the PCB exceeds limits.

A device comprises a voltage regulator, circuits, a voltage-to-current converter, a control bus, a resistor and a resistor network. Each of the circuits has at least one LED connector and one LED driver. Each of the circuits has a measuring circuit for detecting voltage differences between the potentials of LED terminals and a reference potential. Further, each of the circuits includes a local controller. The local controller withdraws a current from the control bus in dependence on the detected voltage differences. Bias current sources inject bias currents into the control bus in form of a sum current of the injected bias currents. The resistor performs a current-to-voltage conversion of the sum current to a control voltage. The voltage-to-current converter converts the control voltage into a current. The resistor network converts the current into a voltage value. An output voltage of the voltage regulator depends on the voltage value.

A device comprises a voltage regulator, circuits, a voltage-to-current converter, a control bus, a resistor and a resistor network. Each of the circuits has at least one LED connector and one LED driver. Each of the circuits has a measuring circuit for detecting voltage differences between the potentials of LED terminals and a reference potential. Further, each of the circuits includes a local controller. The local controller withdraws a current from the control bus in dependence on the detected voltage differences. Bias current sources inject bias currents into the control bus in form of a sum current of the injected bias currents. The resistor performs a current-to-voltage conversion of the sum current to a control voltage. The voltage-to-current converter converts the control voltage into a current. The resistor network converts the current into a voltage value. An output voltage of the voltage regulator depends on the voltage value.

A method supplies a lighting device with electrical energy, wherein the lighting device includes at least two integrated circuits with at least one LED group by a current source associated with this LED group. The method includes generating a supply voltage by a voltage regulator, adjusting a LED group current passing the LED groups by one of the respective current sources, detecting the voltage drops across the current sources, selecting one voltage drop of each integrated circuit as a characteristic voltage drop, generating a control value of the respective integrated circuit, according to the characteristic voltage drop, reducing the control voltage when the control voltage is greater than a control value of the respective integrated circuit, and controlling the output voltage in accordance with the control voltage and/or in accordance with a control bus voltage derived from the control voltage.

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 control circuit for a voltage source generates a reference signal for a voltage source, wherein the reference signal indicates a requested output voltage to be generated by the voltage source. A digital feed-forward control circuit computes a digital feed-forward regulation value indicative of a requested output voltage by determining a maximum voltage drop at strings of solid-state light sources. A digital feed-back control circuit determines a minimum voltage drop for current regulators/limiters for the strings and determines a digital feed-back correction value as a function of the minimum voltage drop. The control circuit then sets the reference signal after a start-up as a function of the digital feed-forward regulation value and corrects the reference signal as a function of the digital feed-back correction value.

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.