A DC-DC converter supplies an output voltage to a plurality of channels of a light emitting device array in common. A current driver has a plurality of driver units which drive the channels. Each of the driver units includes a drive transistor and a detector which detects an abnormality of a drive current. A logic unit generates digital data in response to a plurality of detection signals and supplies the same to a D/A converter. An analog reference voltage of the D/A converter is supplied to the DC-DC converter. The logic unit executes a calibration operation which determines digital data for setting the minimum output DC voltage at the normal operation of all the channels by sequential updating of the digital data.

Semiconductor integrated circuit and operation method thereof

A light emitting diode (LED) lamp includes an LED cluster including LED groups arranged in series, a power source configured to provide an input power to the LED cluster, and a driving unit configured to adjust a number of the LED groups connected to a current path of the LED cluster in series based on the input power to the LED cluster.

Continuous step driver

A light emitting diode (LED) controller for controlling a plurality of LED channels includes channel select circuitry, detection circuitry, and error processor circuitry The channel select circuitry is configured to drive N-l LED channels of a plurality of LED channels at a nominal modulation frequency and to selectively drive a selected one of the N LED channels at a probe modulation frequency The detection circuitry is configured to receive a composite brightness signal corresponding to brightness signals from the N LED channels The detection circuitry is further configured to filter the composite bright signal and generate a selected brightness signal corresponding to a brightness of the selected LED channel at the probe modulation frequency The error processor circuitry is configured to compare the selected brightness signal to user defined and/or preset photometric quantities and generate a control signal for adjusting the brightness of the selected LED channel

LED control using modulation frequency detection techniques

A multi-channel LED driver includes a plurality of linear current regulators, each connected to a bottom of a string of series connected LEDs of a multi-channel LED that controls a bias current and the string of series connected LEDs responsive to an LED bias reference voltage. A dynamic headroom regulation voltage control circuit monitors the headroom regulation voltage at the bottom of each string of the series connected LEDs in the multi-channel LED and generates a reference voltage controlling each of the headroom regulation voltages responsive to the LED bias reference voltage.

LED driver with adaptive dynamic headroom voltage control

A power source control method for a multi-module light-emitting diode (LED) circuit includes detecting a signal characteristics value according to a plurality of switching signals, being used for controlling the conduction of currents in the plurality of lighting modules, comparing the signal characteristics value with a pre-determined value to generate a comparing result, and outputting the comparing result to an external power supply device, such that the external power supply device can adjust the voltage level of an input voltage of the multi-module LED circuit according to the comparing result.

Power Source Control Method for a Multi-module LED Circuit and Related Control Device and LED Circuit

A power management technique in a light emitting diode (LED) system is disclosed. The LED system includes a plurality of LED driver connected in series, each LED driver configured to regulate the current flowing through a corresponding subset of a plurality of LED strings. Each LED driver determines the minimum tail voltage of the LED strings of the corresponding subset, compares the determined minimum tail voltage with an indicator of a minimum tail voltage of one or more other subsets provided from an upstream LED driver in the series, and then provides an indicator of the lower of the two tail voltages to the downstream LED driver. In this manner an indicator of the minimum tail voltage of the plurality of LED strings is cascaded through the series. A feedback controller monitors the minimum tail voltage represented by the cascaded indicator and accordingly adjusts an output voltage provided to the head ends of the plurality of LED strings.

Bin Zhao

Papers

Serial configuration for dynamic power control in LED displays