Described herein are systems and methods for operating DC-DC regulators such as LED drivers. Various embodiments herein allow a DC-DC regulator to switch between buck mode and buck-boost mode without suffering effects otherwise resulting from transient currents when switching between modes. In certain embodiments, this is accomplished by operating the DC-DC regulator in a buck-boost mode to charge a boost capacitor with a substantially constant inductor current. The inductor current is also used to control a set of switches to operate the DC-DC regulator in a buck mode to drive a load by using the capacitor as a power source.

An LED driver is described, the LED driver comprising: a back end module BE comprising a switch mode power converter SMPS configured to operate in a self-oscillating current control mode, the back end module BE further comprising: an input terminal configured to receive a DC bus voltage; an output terminal configured to output a supply current for powering an LED fixture; a control unit configured to control the back end module to operate the SMPS in a voltage control mode by: determining a switching frequency of the SMPS when operating in the self-oscillating current control mode; determining a minimal switching frequency of the SMPS and receiving an input signal representative of the supply current for powering the LED fixture; wherein the control unit is further configured to control the switch of the SMPS in the voltage control mode by: operating the switch of the SMPS at a substantially constant frequency based on the determined minimal switching frequency and modulating a duty cycle of the switch to maintain the supply current at a desired current.

The current regulation system, providing fine dimming control, has an under-voltage circuit, an over-temperature control circuit, and sometimes a variable resistor (VR) control circuit. The under-voltage and over-temperature controls (first and second control signals) pass through voltage limiters such that the lowest level voltage control signal is applied to the voltage reference signal IREF input of LED IC driver. IC driver has a voltage reference input IREF which controls an IC output current for an LED load demand. The VR control generates a third control signal at the junction to reduce the voltage reference signal under control of the VR. The lowest level control signal dims the LED lamps. Since low level voltage control signals are used, a low voltage turn OFF circuit applies an IC disablement signal to the LED IC driver input control based upon sensing a very low voltage at the junction.

A two-way load control system comprises a power device, such as a load control device for controlling an electrical load receiving power from an AC power source, and a controller adapted to be coupled in series between the source and the power device. The load control system may be installed without requiring any additional wires to be run, and is easily configured without the need for a computer or an advanced commissioning procedure. The power device receives both power and communication over two wires. The controller generates a phase-control voltage and transmits a forward digital message to the power device by encoding digital information in timing edges of the phase-control voltage. The power device transmits a reverse digital message to the controller via the power wiring.

A two-way load control system comprises a power device, such as a load control device for controlling an electrical load receiving power from an AC power source, and a controller adapted to be coupled in series between the source and the power device. The load control system may be installed without requiring any additional wires to be run, and is easily configured without the need for a computer or an advanced commissioning procedure. The power device receives both power and communication over two wires. The controller generates a phase-control voltage and transmits a forward digital message to the power device by encoding digital information in timing edges of the phase-control voltage. The power device transmits a reverse digital message to the controller via the power wiring.

The embodiments of the present application disclose a booster circuit and a driving method thereof, a backlight module and a display device. The booster circuit includes: a booster sub-circuit and an oscillation elimination sub-circuit; wherein the booster sub-circuit includes a power supply element, an inductor, and a first switch; the booster sub-circuit is configured to provide, at a connection node, a voltage higher than a voltage provided from the power supply element; and wherein a parasitic capacitance occurs between the connection node and a ground terminal; the oscillation elimination sub-circuit is configured to prevent a current generated when the parasitic capacitance discharges from flowing through the inductor so as to eliminate an oscillation generated between the parasitic capacitance and the inductor.

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 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 an electrical load is configured to operate in a normal mode and a burst mode to adjust the amount of power delivered to the electrical load. The load control device comprises a control circuit that operates in the normal mode to regulate an average magnitude of a load current conducted through the load between a maximum rated current and a minimum rated current. During the normal mode, the control circuit controls the operating period of a load regulation circuit between a high-end operating period and a low-end operating period. The control circuit operates in the burst mode to regulate the average magnitude of the load current below the minimum rated current. During the burst mode, the control circuit adjusts the low-end operating period to be less than or equal to a minimum on time of the load regulation circuit.

A load control device for an electrical load is configured to operate in a normal mode and a burst mode to adjust the amount of power delivered to the electrical load. The load control device comprises a control circuit that operates in the normal mode to regulate an average magnitude of a load current conducted through the load between a maximum rated current and a minimum rated current. During the normal mode, the control circuit controls the operating period of a load regulation circuit between a high-end operating period and a low-end operating period. The control circuit operates in the burst mode to regulate the average magnitude of the load current below the minimum rated current. During the burst mode, the control circuit adjusts the low-end operating period to be less than or equal to a minimum on time of the load regulation circuit.