Abstract: A current sampling circuit with on-chip real-time calibration is used to detect the on-state current of a driving transistor. The current sampling circuit includes a first resistor, a second resistor, a voltage sampling circuit, a sampling voltage operational circuit and an on-state resistance calibration circuit. The voltage sampling circuit is used to obtain on-state voltage drop value of the driving transistor Vds. The on-state resistance calibration circuit includes a reference current source and a calibrating transistor. On-state resistance value of the calibrating transistor is set to be K1 times of on-state resistance value of the driving transistor. The on-state voltage drop value Vds obtained by the voltage sampling circuit and the on-voltage drop value of the calibrating transistor Vrsns are input to the sampling voltage operational circuit to obtain proportional relationship K2 between the on-state voltage drop value Vds and the on-state voltage drop value Vrsns.

Abstract: A pulse width modulation (PWM) circuit and method are presented. The circuit has a switch for repeatedly coupling and decoupling a circuit element to a current source. The circuit also has feedback circuitry to detect a current flowing through the circuit element. The circuit also has a PWM generator to provide a digital signal to the switch and to adjust the digital signal in response to the detected current.

Abstract: A current sampling circuit with on-chip real-time calibration is used to detect the on-state current of a driving transistor. The current sampling circuit includes a first resistor, a second resistor, a voltage sampling circuit, a sampling voltage operational circuit and an on-state resistance calibration circuit. The voltage sampling circuit is used to obtain on-state voltage drop value of the driving transistor Vds. The on-state resistance calibration circuit includes a reference current source and a calibrating transistor. On-state resistance value of the calibrating transistor is set to be K1 times of on-state resistance value of the driving transistor. The on-state voltage drop value Vds obtained by the voltage sampling circuit and the on-voltage drop value of the calibrating transistor Vrsns are input to the sampling voltage operational circuit to obtain proportional relationship K2 between the on-state voltage drop value Vds and the on-state voltage drop value Vrsns.

Abstract: A lighting system and a method are provided with an adaptive power balancing scheme which reduces or eliminates flicker by sensing the operation of a lamp that is connected to an electronic transformer and adaptively controlling the drive circuit of the lamp to prevent unexpected reset of the electronic transformer. There is provided a lamp with a light source and a drive circuit for the light source; said drive circuit has a power stage for regulating a voltage supplied to the light source, an energy storage device, and control means arranged to selectively disable the power stage. Power is provided to the light source by the energy storage device when the power stage is disabled.

Abstract: There is presented a current driver and a corresponding method for driving a current-controlled component such as a semiconductor light source with a driving current. The current driver includes a current regulator for regulating the driving current, a power circuit, and an input stage. The input stage receives a first signal and a second signal and is operable in two phases. In the first phase, the first signal is used to power the power circuit, and in the second phase, the second signal is used to power the power circuit. The current driver may be implemented in an array of cells in which each cell includes a current driver coupled to a current controlled component. The array of cells may be a part of a display device.

Abstract: A light emitting diode (LED) circuit for preventing parasitic current flow through a first LED when the first LED is in an off state is described, where the parasitic current flow is a result of one or more parasitic capacitances, the LED circuit comprising the first LED, and a first current switch coupled to the first LED and arranged to enable a current flow through the first LED when the first current switch is in an on state, where the first current switch is arranged to discharge the one or more parasitic capacitances when the first current switch is in the on state.

Abstract: A serial communication protocol for daisy-chained slave devices does away with the requirement for an entire byte of dummy clocks to be cycled between a slave's input and output, instead requiring a shorter set of dummy clock cycles which improves efficiency of a serial communication system. According to a specification of a serial communications protocol, data is exchanged between master and slave devices in communication frames. Each communication frame has a command portion and a data portion, and each respective portion may comprise packages of one or more bytes.

Abstract: A method and an apparatus for charge recycling. The method is comprised of the steps of receiving a charge at an energy storage element from a parasitic component, storing the charge at the energy storage element, and providing the charge stored at the energy storage element to a power supply's input or output. The step of receiving the charge at the energy storage element includes operating a discharging switch to selectively couple the parasitic component with the energy storage element and receiving the charge at the energy storage element via the discharging switch when the energy storage element and the parasitic component are coupled.

Abstract: A dimmer for dimming light emitted by a light source is presented. The dimmer includes a regulation switch for regulating a current flowing through the light source and a regulator circuit that provides an electronic parameter to control the regulation switch. The regulator circuit has a dimmer switch for passing or blocking the electronic parameter, and a signal generator generating a plurality of modulated signals configured to operate the regulator circuit in a first phase and in a second phase. In the first phase the regulation circuit maintains the electronic parameter to a target value. In the second phase the regulation circuit monitors a variation of the electronic parameter and maintains the electronic parameter to a predetermined value.

Abstract: The present disclosure relates to an apparatus and method for driving a switch, such as a power switch. A driver comprises a voltage sensor to sense a drive voltage, and an electrical source to provide a drive signal having a drive value. The driver is adapted to adjust the drive value based on the drive voltage to limit a switch-current flowing through the switch.

Abstract: A pulse width modulation (PWM) circuit and method are presented. The circuit has a switch for repeatedly coupling and decoupling a circuit element to a current source. The circuit also has feedback circuitry to detect a current flowing through the circuit element. The circuit also has a PWM generator to provide a digital signal to the switch and to adjust the digital signal in response to the detected current.

Abstract: A method and an apparatus for charge recycling. The method is comprised of the steps of receiving a charge at an energy storage element from a parasitic component, storing the charge at the energy storage element, and providing the charge stored at the energy storage element to a power supply's input or output. The step of receiving the charge at the energy storage element includes operating a discharging switch to selectively couple the parasitic component with the energy storage element and receiving the charge at the energy storage element via the discharging switch when the energy storage element and the parasitic component are coupled.

Abstract: A serial communication protocol for daisy-chained slave devices does away with the requirement for an entire byte of dummy clocks to be cycled between a slave's input and output, instead requiring a shorter set of dummy clock cycles which improves efficiency of a serial communication system. According to a specification of a serial communications protocol, data is exchanged between master and slave devices in communication frames. Each communication frame has a command portion and a data portion, and each respective portion may comprise packages of one or more bytes.

Abstract: This specification relates to a method and a system for detecting light emitting diode (LED) short circuit in a plurality of LED strings or detecting matching among the plurality of LED strings, wherein one end of each of the plurality of LED strings is connected to a same output end of a power supply, and the other end is respectively connected to a corresponding switch. According to the present invention, first current of each of LED strings is obtained when the output end of the power supply outputs a first voltage; differences between the minimum of the first currents of LED strings and other first currents are calculated; the differences are compared with a comparing threshold; it is determined that the LED strings corresponding to the other currents for which differences are larger than the comparing threshold include short circuit or mismatch with the LED string corresponding to the minimum current. Accordingly, it is possible to reduce the number of pins and area of a control chip.

Abstract: An electronic device is provided that includes an integrated circuit (IC) configured to regulate an output voltage for powering a light emitting diode (LED). A first transistor is configured to be switched on or off by the IC to inductively couple or decouple a main power supply bus voltage from a primary winding of a transformer to a secondary winding of the transformer connectable to the LED. A second transistor is coupled between the IC and the main power supply bus voltage, and configured to be switched on or off by the IC to selectively provide an IC power supply input voltage to the IC.

Abstract: A light emitting diode (LED) circuit for preventing parasitic current flow through a first LED when the first LED is in an off state is described, where the parasitic current flow is a result of one or more parasitic capacitances, the LED circuit comprising the first LED, and a first current switch coupled to the first LED and arranged to enable a current flow through the first LED when the first current switch is in an on state, where the first current switch is arranged to discharge the one or more parasitic capacitances when the first current switch is in the on state.

Abstract: The present disclosure relates to an apparatus and method for driving a switch, such as a power switch. A driver comprises a voltage sensor to sense a drive voltage, and an electrical source to provide a drive signal having a drive value. The driver is adapted to adjust the drive value based on the drive voltage to limit a switch-current flowing through the switch.

Abstract: An electronic that includes an integrated circuit (IC) configured to regulate an output voltage for powering a light emitting diode (LED). A first transistor is configured to be switched on or off by the IC to inductively couple or decouple a main power supply bus voltage from a primary winding of a transformer to a secondary winding of the transformer connectable to the LED. A second transistor is coupled between the IC and the main power supply bus voltage, and configured to be switched on or off by the IC to selectively provide an IC power supply input voltage to the IC.

Abstract: Systems, methods, and apparatus for a circuit with adaptive switching frequency control are disclosed. The method comprises operating a controller of the dimmable single-stage power converter in pulse width modulation (PWM) mode at a first switching frequency level from a maximum dimming duty-ratio level until a first dimming duty-ratio level. The method further comprises operating the controller in PWM mode, while reducing switching frequency from the first switching frequency level to a second switching frequency level, from the first dimming duty-ratio level until a second dimming duty-ratio level. Also, the method comprises operating the controller in PWM mode at the second switching frequency level from the second dimming duty-ratio level until a current command (Vipk) falls below a predetermined low limit value. Further, the method comprises operating the controller in skip mode, while reducing the switching frequency from the second switching frequency level, until a minimum dimming duty-ratio level.

Abstract: An electronic that includes an integrated circuit (IC) configured to regulate an output voltage for powering a light emitting diode (LED). A first transistor is configured to be switched on or off by the IC to inductively couple or decouple a main power supply bus voltage from a primary winding of a transformer to a secondary winding of the transformer connectable to the LED. A second transistor is coupled between the IC and the main power supply bus voltage, and configured to be switched on or off by the IC to selectively provide an IC power supply input voltage to the IC.