Abstract: An LED lighting device includes a slave driving stage and a master driving stage. The slave driving stage includes a first luminescent device and a first current controller for providing a constant current setting in an ON phase. The master driving stage includes a second luminescent device and a current control unit having a second current controller and a current envelope controller. The second current controller provides a current envelope in the ON phase. The current envelope controller sets a level of the current envelope according to a rectified AC voltage. The driving current is regulated by the first current controller according to the constant current setting when the constant current setting is smaller than the level of the current envelope, or by the second current controller according to the current envelope when the level of the current envelope is smaller than the constant current setting.

Abstract: An LED lighting device includes multiple driving stages. A first driving stage includes a first luminescent device driven by a first current and a first current controller coupled in parallel with the first luminescent device. The first current controller is configured to conduct a second current according to a voltage established across the first current controller and regulate the second current so that a sum of the first current and the second current does not exceed a first value. The second driving stage includes a second luminescent device driven by a third current and a second current controller coupled in series to the second luminescent device. The second current controller is configured to conduct a fourth current according to a voltage established across the second current controller and regulate the fourth current so that a sum of the third current and the fourth current does not exceed a second value.

Abstract: A two-terminal current controller controls a first current flowing through a parallel-coupled load. During a rising period of a rectified AC voltage, when a load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode. When the load voltage exceeds the first voltage but does not exceed a second voltage, the two-terminal current controller operates in a second mode. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode. When the load voltage drops to a third voltage smaller than the second voltage after exceeding the second voltage, the two-terminal current controller operates in the second mode when a difference between the second and third voltages exceeds a hysteresis band and operates in the third mode when a difference between the second and third voltages does not exceed the hysteresis band.

Abstract: A digitally controlled voltage generator is disclosed for use in applications requiring fine resolution voltage control, such as generating a common voltage for a liquid crystal display. A constant resistance digital to analog converter (DAC) is configured to provide appropriate voltage steps by tuning bias resistors to generate desirable reference voltages for the DAC. The bias resistors are configured to be tuned after placement and routing steps in an integrated circuit design.

Abstract: A light emitting diode luminance system includes a first power source, a voltage divider, a first switch, a clamping device, a plurality of current sources and a feedback circuit. The voltage divider is coupled to the first voltage source. The first switch is coupled to the voltage divider and a ground. The clamping device includes a plurality of transistors each coupled to a respective set of light emitting diodes and the voltage divider. The plurality of current sources is coupled to the plurality of transistors respectively. The feedback circuit is coupled to the plurality of transistors and the plurality sets of light emitting diodes.

Abstract: An LED lighting device includes a first luminescent device, a second luminescent device, a first current controller and a second current controller. The first current controller is coupled in parallel with the first luminescent device and configured to operate according to a first current setting, a switch-on voltage and a switch-off voltage. The second current controller is coupled in series to the second luminescent device and configured to operate according to a second current setting. The first current setting, the second current setting, the switch-on voltage and the switch-off voltage are adjusted by setting the mode selection pins of the first and second current controllers.

Abstract: A backlight driver includes current sources that are connected between LED strings and a number of bias voltages. There can be any number of different bias voltages, each at a ground potential or higher voltage. The bias voltage is selected for a particular LED string in order to reduce a current drop across the current source. This reduces the power consumption of the current source and LED string. Heat dissipation is also reduced.

Abstract: The present invention provides a light source dimming control circuit, which includes a voltage signal generator for generating a first voltage signal between a predetermined voltage level and a ground level; a reference voltage signal generator for generating a reference voltage signal at an output end according to the first voltage signal and a second voltage signal; a first switch with a first end coupled to an output end of alight source; a first resistor with a first end coupled to a second end of the first switch, and a second end coupled to a ground end; a switch controller coupled to the first switch and the voltage signal generator for controlling on/off states of the first switch according to a sawtooth signal and the first voltage signal; and a current controller for controlling current flowing through the first resistor according to the reference voltage signal.

Abstract: A digitally controlled voltage generator is disclosed for use in applications requiring fine resolution voltage control, such as generating a common voltage for a liquid crystal display. A constant resistance digital to analog converter (DAC) is configured to provide appropriate voltage steps by tuning bias resistors to generate desirable reference voltages for the DAC. The bias resistors are configured to be tuned after placement and routing steps in an integrated circuit design.

Abstract: A light emitting diode luminance system includes a first power source, a voltage divider, a first switch, a clamping device, a plurality of current sources and a feedback circuit. The voltage divider is coupled to the first voltage source. The first switch is coupled to the voltage divider and a ground. The clamping device includes a plurality of transistors each coupled to a respective set of light emitting diodes and the voltage divider. The plurality of current sources is coupled to the plurality of transistors respectively. The feedback circuit is coupled to the plurality of transistors and the plurality sets of light emitting diodes.

Abstract: An LED lighting device includes a first luminescent device for providing light according to a first current, a second luminescent device coupled in series to the first luminescent device for providing light according to a second current, an impedance device for limiting the second current within a predetermined range when a voltage established across the first luminescent device and the second luminescent device exceeds a first predetermined value, and a two-terminal current controller coupled in parallel with the first luminescent device and in series to the second luminescent device and configured to regulate the second current according to a voltage established across the two-terminal current controller.

Abstract: A two-terminal current controller having a current limiting unit and an adjusting unit regulates a first current flowing through a load according to a load voltage. When the load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode for conducting a second current associated a rectified AC voltage, thereby limiting the first current to zero and adjusting the second current accordingly. When the load voltage is between the first voltage and a second voltage, the two-terminal current controller operates in a second mode for conducting the second current, thereby limiting the first current to zero and limiting the second current to a constant value larger than zero. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode for turning off the current limiting unit. The adjusting unit can adjust the predetermined value and the second voltage.

Abstract: A two-terminal current controller having a current limiting unit and an adjusting unit regulates a first current flowing through a load according to a load voltage. When the load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode for conducting a second current associated a rectified AC voltage, thereby limiting the first current to zero and adjusting the second current accordingly. When the load voltage is between the first voltage and a second voltage, the two-terminal current controller operates in a second mode for conducting the second current, thereby limiting the first current to zero and limiting the second current to a constant value larger than zero. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode for turning off the current limiting unit. The adjusting unit can adjust the predetermined value and the second voltage.

Abstract: An LED lighting device includes a first luminescent device for providing light according to a first current, a second luminescent device coupled in series to the first luminescent device for providing light according to a second current, a silicon-controlled rectifier coupled in parallel to the first luminescent device and configured to conduct a third current when a voltage established across the first luminescent device exceeds a break-over voltage, and a two-terminal current controller coupled in parallel with the first luminescent device and in series to the second luminescent device and configured to regulate the second current according to a voltage established across the two-terminal current controller.

Abstract: A two-terminal current controller having a current limiting unit and an adjusting unit regulates a first current flowing through a load according to a load voltage. When the load voltage does not exceed a first voltage, the two-terminal current controller operates in a first mode for conducting a second current associated a rectified AC voltage, thereby limiting the first current to zero and adjusting the second current accordingly. When the load voltage is between the first voltage and a second voltage, the two-terminal current controller operates in a second mode for conducting the second current, thereby limiting the first current to zero and limiting the second current to a constant value larger than zero. When the load voltage exceeds the second voltage, the two-terminal current controller operates in a third mode for turning off the current limiting unit. The adjusting unit can adjust the predetermined value and the second voltage.

Abstract: A two-terminal current controller regulates a first current flowing through a load, which is coupled in parallel with the two-terminal current controller, according to a voltage established across the two-terminal current controller. When the voltage established across the two-terminal current controller does not exceed a first voltage, the two-terminal current controller conducts a second current related to a rectified AC voltage, thereby limiting the first current to zero and regulating the second current according to the load voltage. When the voltage established across the two-terminal current controller is between the first voltage and a second voltage, the two-terminal current controller conducts the second current, thereby limiting the first current to zero and limiting the second current to a constant value larger than zero. When the voltage established across the two-terminal current controller is greater than second voltage, the two-terminal current controller is turned off.

Abstract: Constant current driving circuit includes a latch, an ON timer, and an OFF timer. The latch outputs a switch control signal according to an ON signal and an OFF signal for controlling a power switch. The power switch is coupled between an input voltage source and an inductor. When the switch control signal controls the power switch to turn on/off, the input voltage source is able/unable to couple to the inductor through the power switch. The inductor provides an output current and an output voltage. The ON timer detects if the output current reaches a peak value for accordingly outputting the OFF signal. The OFF timer outputs the ON signal according to the output voltage and the switch control signal for control the interval of the switch control signal representing “OFF”.

Abstract: A two-terminal current controller regulates a first current flowing through a load, which is coupled in parallel with the two-terminal current controller, according to a voltage established across the two-terminal current controller. When the voltage established across the two-terminal current controller does not exceed a first voltage, the two-terminal current controller conducts a second current related to a rectified AC voltage, thereby limiting the first current to zero and regulating the second current according to the load voltage. When the voltage established across the two-terminal current controller is between the first voltage and a second voltage, the two-terminal current controller conducts the second current, thereby limiting the first current to zero and limiting the second current to a constant value larger than zero. When the voltage established across the two-terminal current controller is greater than second voltage, the two-terminal current controller is turned off.

Abstract: In one embodiment, a method includes: detecting one of a short-to-ground condition and a short-to-supply condition at an output node; selectively activating a feedback control transistor according to the detecting; detecting a first current passing through a first transistor using a second transistor sized to be smaller than the first transistor; mirroring the detected current using a plurality of transistors to form a feedback current; and providing the feedback current to a gate electrode of the first transistor according to the selectively activating the feedback control transistor.

Abstract: A DC power conversion circuit with constant current output includes a DC voltage source, a driving circuit and a control signal generator. The DC voltage source is used for providing DC power. The driving circuit includes a switch, a resistor, a diode, and an inductor. The switch has three ends, one used for receiving a control signal. Furthermore, the switch is used for conducting or cutting off a coupling between the other two ends according to the control signal. The resistor is coupled between the switch and a first grounding end. The diode has a first end and a second end coupled to a second grounding end. The inductor has a first end coupled to the first grounding end, and a second end coupled to a load circuit. The control signal generator generates the control signal for the second end of the switch according to a current of the resistor.