Patent application number | Description | Published |
20080309380 | METHOD AND APPARATUS FOR DETECTING SWITCHING CURRENT OF MAGNETIC DEVICE OPERATED IN CONTINUOUS CURRENT MODE - The present invention provides a method and apparatus for detecting a continuous current of a switching current. A current signal is produced in response to a switching current of the magnetic device. By sampling the waveform of the current signal in response to the enabling of a switching signal, a first current signal and a second current signal are generated. A continuous current signal is produced according to the first current signal and the second current signal. The continuous current signal is corrected to the continuous current of the switching current. | 12-18-2008 |
20090058389 | CONTROL CIRCUIT FOR MEASURING AND REGULATING OUTPUT CURRENT OF CCM POWER CONVERTER - A switching control circuit is provided for measuring and regulating an output current of a power converter. The power converter is operated under continuous current mode. A detection circuit generates a continuous-current signal and a peak-current signal by detecting a switching current of an inductive device. An integration circuit generates an average-current signal in response to the continuous-current signal, the peak-current signal and an off time of a switching signal. The switching control circuit generates the switching signal in response to the average-current signal. The switching signal is coupled to switch the inductive device and regulate the output current of the power converter. A time constant of the integration circuit is correlated to the switching period of the switching signal, therefore the average-current signal will be proportional to the output current. | 03-05-2009 |
20090310388 | METHOD AND APPARATUS FOR MEASURING THE SWITCHING CURRENT OF POWER CONVERTER OPERATED AT CONTINUOUS CURRENT MODE - An apparatus for detecting a switching current of the power converter, wherein the apparatus includes a signal generation circuit, a sample-and-hold circuit, and a calculating circuit. The signal generation circuit generates a sample signal in accordance with the pulse width of a switching signal. The sample-and-hold circuit is coupled to receive the sample signal and switching current signal for generating a first current signal and a second current signal. The calculating circuit is coupled to receive the first current signal and the second current signal for generating output signals. The switching signal is used for switching the magnetic device of the power converter, and the switching current signal is correlated to the switching current of the power converter; the output signals are correlated to the value of the switching current of the power converter. | 12-17-2009 |
20100097104 | CONTROL CIRCUIT HAVING OFF-TIME MODULATION TO OPERATE POWER CONVERTER AT QUASI-RESONANCE AND IN CONTINUOUS CURRENT MODE - A control circuit is developed to adaptively operate a power converter at quasi-resonance (QR) and in a continuous current mode (CCM) to achieve high efficiency. The control circuit includes a PWM circuit generating a switching signal coupled to switch a transformer. A signal generation circuit generates a ramp signal and a pulse signal. The pulse signal is generated in response to the ramp signal for switching on the switching signal. A feedback circuit produces a feedback signal according to an output load of the power converter. The feedback signal is coupled to switch off the switching signal. A detection circuit is coupled to the transformer for generating a valley signal in response to the waveform of the transformer. The valley signal is further coupled to generate the pulse signal when the ramp signal is lower than a threshold. The level of the threshold is correlated to the feedback signal. | 04-22-2010 |
20100232187 | OUTPUT VOLTAGE CONTROL CIRCUIT OF POWER CONVERTER FOR LIGHT-LOAD POWER SAVING - A control circuit of a power converter for light-load power saving according to the present invention comprises a first feedback circuit coupled to an output voltage of the power converter to receive a first feedback signal. A second feedback circuit is coupled to the output voltage to receive a second feedback signal. A control circuit generates a switching signal for switching a transformer of the power converter and regulating the output voltage of the power converter in response to the first feedback signal and the second feedback signal. The switching signal is generated in accordance with the first feedback signal when an output load is high. The switching signal is generated in accordance with the second feedback signal during a light-load condition. | 09-16-2010 |
20110169418 | LED DRIVE CIRCUIT WITH A PROGRAMMABLE INPUT FOR LED LIGHTING - A LED drive circuit according to the present invention comprises a controller and a programmable signal. The controller generates a switching signal coupled to switch a magnetic device for generating an output current to drive a plurality of LEDs. The programmable signal is coupled to regulate a current-control signal of the controller. The switching signal is modulated in response to the current-control signal for regulating the output current, and the level of the output current is correlated to the current-control signal. | 07-14-2011 |
20110254537 | Method and Apparatus for Detecting CCM Operation of a Magnetic Device - A method and an apparatus for detecting a CCM operation of a magnetic device are developed. The method generates a current signal in accordance with a switching current of the magnetic device and generates a first current signal and a second current signal by sampling the current signal. A mode signal is further generated according to the first current signal and the second current signal. The mode signal indicates the magnetic device is operated in CCM or DCM. The apparatus comprises a first sample circuit, a second sample circuit, and an arbiter. The first sample circuit samples the current signal to generate the first current signal. The second sample circuit samples the current signal to generate the second current signal. The arbiter generates the mode signal according to the first current signal and the second current signal for indicating the magnetic device is operated in CCM or DCM. | 10-20-2011 |
20120081039 | METHOD AND APPARATUS FOR A LED DRIVER WITH HIGH POWER FACTOR - A control circuit of a LED driver according to the present invention comprises an output circuit, an input circuit and an input-voltage detection circuit. The output circuit generates a switching signal to produce an output current for driving at least one LED in response to a feedback signal. The switching signal is coupled to switch a transformer. The input circuit samples an input signal for generating the feedback signal. The input signal is correlated to the output current of the LED driver. The input-voltage detection circuit generates an input-voltage signal in response to an input voltage of the LED driver. The input circuit will not sample the input signal when the input-voltage signal is lower than a threshold. The control circuit can eliminate the need of the input capacitor for improving the reliability of the LED driver. | 04-05-2012 |
20140232284 | LED DRIVE CIRCUIT WITH A PROGRAMMABLE INPUT FOR LED LIGHTING - A LED drive circuit according to the present invention comprises a controller and a programmable signal. The controller generates a switching signal coupled to switch a magnetic device for generating an output current to drive a plurality of LEDs. The programmable signal is coupled to regulate a current-control signal of the controller. The switching signal is modulated in response to the current-control signal for regulating the output current, and the level of the output current is correlated to the current-control signal. | 08-21-2014 |