Patent application number | Description | Published |
20090058323 | Flyback LED drive circuit with constant current regulation - A flyback LED drive circuit for the plurality of LEDs is provided. An inductive device is coupled to an input voltage. A power transistor is connected to the inductive device in series to control the switching current of the inductive device. The energy is stored into the inductive device when the power transistor is turned on. The stored energy is delivered to the plurality of LEDs via a flyback diode when the power transistor is turned off. A control circuit is utilized to detect the switching current of the inductive device for generating a switching signal to provide a constant current to the plurality of LEDs. | 03-05-2009 |
20090141521 | Method and apparatus of providing synchronous regulation for offline power converter - A synchronous regulation circuit is provided to improve the efficiency for an offline power converter. A secondary-side switching circuit is coupled to the output of the power converter to generate a synchronous signal and a pulse signal in response to an oscillation signal and a feedback signal. An isolation device transfers the synchronous signal from the secondary side to the primary side of the power converter. A primary-side switching circuit further receives the synchronous signal to generate a switching signal for soft switching a transformer. The pulse signal is utilized to control a synchronous switch for rectifying and regulating the power converter. The synchronous switch includes a power switch and a control circuit. The control circuit receives the pulse signal for turning on/off the power switch. The power switch is connected in between the transformer and the output of the power converter. In addition, a flyback switch is operated as a synchronous rectifier to freewheel the inductor current of the power converter. The flyback switch is turned on in response to the off of the power switch. The on time of flyback switch is correlated to the on time of the power switch. | 06-04-2009 |
20090219000 | SWITCHING CONTROLLER WITH BURST MODE MANAGEMENT CIRCUIT TO REDUCE POWER LOSS AND ACOUSTIC NOISE OF POWER CONVERTER - A switching controller of power converter according to the present invention comprises a PWM circuit and a burst-mode management circuit to reduce the power loss and the acoustic noise of the power converter at light-load. The PWM circuit generates a PWM signal. The burst-mode management circuit receives the PWM signal to generate a switching signal for generating a switching current and regulating the output of the power converter. The burst-mode management circuit further generates a current-limit signal in response to the output of the power converter to limit the switching current for reducing the power loss and the acoustic noise of the power converter when the power converter is at light-load. | 09-03-2009 |
20090237133 | SWITCHING CONTROL CIRCUIT FOR MULTI-CHANNELS AND MULTI-PHASES POWER CONVERTER OPERATED AT CONTINUOUS CURRENT MODE - A switching control circuit for multi-channels and multi-phases power converter according to the present invention comprises a master control circuit and a slave control circuit. The master control circuit generates a multiplier signal in response to an input voltage and an output voltage of the power converter, and generates a first switching signal to switch a first inductor of the power converter in accordance with the multiplier signal and the first-current signal generated by a first current-sense device. The slave control circuit generates a second switching signal to switch a second inductor of the power converter in accordance with the multiplier signal, the first switching signal and a second-current signal generated by a second current-sense device. Once the power converter is at light-load, the multiplier signal is disabled to turn off the second switching signal to turn off the slave control circuit for power saving of the power converter. | 09-24-2009 |
20090256540 | LOW DROP-OUT REGULATOR PROVIDING CONSTANT CURRENT AND MAXIMUM VOLTAGE LIMIT - A low drop-out regulator according to the present invention comprises an unregulated DC input terminal receiving an input voltage. A pass circuit is coupled between the unregulated DC input terminal and a regulated DC output terminal for supplying a power to the regulated DC output terminal. An amplifying circuit controls the pass circuit for providing a constant voltage or/and a constant current in response to an output voltage or/and an output current. | 10-15-2009 |
20090256543 | HIGH EFFICIENCY BRIDGELESS PFC POWER CONVERTER - A bridgeless PFC power converter comprises a first inductor and a second inductor coupled from a first input-terminal and a second input-terminal to a first transistor and a second transistor. A first diode and a second diode are coupled from the first transistor and the second transistor to an output capacitor. A first capacitor and a second capacitor are coupled from the input-terminals to the ground terminal through a third transistor and a fourth transistor. A control circuit generates a first-switching signal and a second-switching signal to control the first transistor and the second transistor. The second-switching signal will turn on the second transistor when the first-switching signal switches the first transistor. The first-switching signal will turn on the first transistor when the second-switching signal switches the second transistor. The control circuit turns off the third transistor and the fourth transistor during the light-load of the PFC power converter. | 10-15-2009 |
20090309634 | TRANSISTOR GATE DRIVING CIRCUIT WITH POWER SAVING OF POWER CONVERTER - A transistor gate driving circuit is developed for power saving. It includes a first high-side transistor, a second high-side transistor and a low-side transistor. A voltage clamp device is connected to the gate terminal of the first high-side transistor to limit the maximum output voltage. A detection circuit is coupled to detect a feedback signal of the power converter. The feedback signal is correlated to the output load of the power converter. The detection circuit will generate a disable signal in response to the level of the feedback signal. The disable signal is coupled to disable the second high-side transistor once the level of the feedback signal is lower than a threshold. | 12-17-2009 |
20120081084 | Controller with Valley Switching and Limited Maximum Frequency for Quasi-Resonant Power Converters - A controller for a power converter is provided. The controller includes a PWM circuit, a detection circuit, a signal generation circuit and an oscillation circuit. The PWM circuit generates a switching signal coupled to switch a transformer of the power converter. A feedback signal is coupled to the PWM circuit to disable the switching signal. The detection circuit is coupled to the transformer via a resistor for generating a valley signal in response to a signal waveform of the transformer. The signal generation circuit is coupled to receive the feedback signal and the valley signal for generating an enabling signal. The oscillation circuit generates a maximum frequency signal. The maximum frequency signal associates with the enabling signal to generate a pulse signal. The feedback signal is correlated to an output load of the power converter. The maximum frequency of the pulse signal is limited. | 04-05-2012 |
20130027988 | SWITCHING CONTROLLER FOR FLYBACK POWER CONVERTERS WITHOUT INPUT CAPACITOR - The present invention proposes a switching controller of a flyback power converter. The switching controller includes a switching circuit, a sample-and-hold circuit, a voltage detection circuit, an oscillation circuit, and a comparator. The voltage detection circuit generates a holding signal when a level of an input voltage of the flyback power converter is lower than a low-threshold. The oscillation circuit limits the maximum frequency of switching signal. The maximum frequency is increased in response to a decrement of a modulation signal. The modulation signal correlated with a level of the input voltage is used to generate a control signal when the level of the input voltage is lower than an ultra-low-threshold. The control signal is enabled to operate the flyback power converter in continuous current mode operation. Therefore, an input capacitor can be eliminated and manufacturing cost is saved. | 01-31-2013 |
20130049812 | MONOLITHIC HIGH-SIDE SWITCH CONTROL CIRCUITS - A high-side switch control circuit is provided. The high-side switch control circuit includes an on/off transistor, a bias resistor, a zener diode, a level-shifting transistor, and a current source. The on/off transistor operates as a switch. The bias resistor is coupled to turn off the on/off transistor. The zener diode is coupled to clamp the maximum voltage of the on/off transistor. The level-shifting transistor is coupled to turn on the on/off transistor. The current source is coupled to the level-shifting transistor. The current source limits the maximum current of the level-shifting transistor. | 02-28-2013 |
20130141056 | ADAPTIVE FREQUENCY COMPENSATION FOR PFC POWER CONVERTER OPERATING IN CCM AND DCM - A control circuit of a power factor correction (PFC) converter is provided. The control circuit includes a pulse width modulation (PWM) circuit, an amplifier, a detection circuit., and a capacitor. The PWM circuit generates a switching signal in response to a loop signal. The amplifier is coupled to generate the loop signal in response to a switching current. The detection circuit generates a mode signal coupled to change output impedance of the amplifier. The capacitor is coupled to the amplifier for loop frequency compensation. The switching signal is coupled to switch an inductor of the PFC power converter and generate the switching current. | 06-06-2013 |
Patent application number | Description | Published |
20120170326 | Primary-side controlled power converter with an RC network and Method thereof - This invention provides a primary-side controlled power converter comprising: an RC network coupled to an auxiliary winding of a transformer of the primary-side controlled power converter to detect a reflected voltage of the transformer for generating a reflected signal, and a controller coupled to the RC network to receive the reflected signal for generating a switching signal; wherein the RC network develops a zero to provide a high-frequency path for shortening a rising time and a settling time of the reflected signal. | 07-05-2012 |
20120212287 | ADAPTIVE FILTER CIRCUIT FOR SAMPLING A REFLECTED VOLTAGE OF TRANSFORMER IN A POWER CONVERTER AND METHOD THEREOF - An adaptive filter circuit for sampling a reflected voltage of a transformer of a power converter includes a first switch for receiving the reflected voltage, a resistor having a first terminal and a second terminal, the first terminal of the resistor being coupled to the first switch, a capacitor coupled to the second terminal of the resistor for holding the reflected voltage, and a second switch coupled to the resistor in parallel, wherein the resistor and the capacitor develop a filter for sampling the reflected voltage which is sampled without filtering by the filter in a first period during a disable period of a switching signal and also sampled with filtering by the filter in a second period during the disable period of the switching signal. | 08-23-2012 |
20120230064 | SWITCHING CONTROLLER WITH VALLEY-LOCK SWITCHING AND LIMITED MAXIMUM FREQUENCY FOR QUASI-RESONANT POWER CONVERTERS - The present invention provides a controller for a power converter. The controller comprises a PWM circuit, a detection circuit, a signal generator, an oscillation circuit, a valley-lock circuit, a timing circuit and a burst circuit. The PWM circuit generates a switching signal coupled to switch a transformer of the power converter. A feedback signal is coupled to control and disable the switching signal. The detection circuit is coupled to the transformer via a resistor for generating a valley signal in response to a waveform obtained from the transformer. The signal generator is coupled to receive the feedback signal and the valley signal for generating an enabling signal. The oscillation circuit generates a maximum frequency signal. The maximum frequency signal associates with the enabling signal to generate a turning-on signal. The turning-on signal is coupled to enable the switching signal. A maximum frequency of the turning-on signal is limited. | 09-13-2012 |
20120306541 | HIGH-SIDE SIGNAL SENSING CIRCUIT - The present invention provides a high-side signal sensing circuit. The high-side signal sensing circuit comprises a signal-to-current converter, a second transistor and a resistor. The signal-to-current converter has a first transistor generating a mirror current in response to an input signal. The second transistor cascaded with the first transistor is coupled to receive the mirror current. The resistor generates an output signal in response to the mirror current. Wherein, the level of the output signal is corrected to the level of the input signal. | 12-06-2012 |