Patent application number | Description | Published |
20090316451 | APPARATUS PROVIDING PROTECTION FOR POWER CONVERTER - A switching circuit for a power converter includes an oscillation circuit, a first circuit, and a first comparator. The oscillation circuit generates a switching signal for regulating an output of the power converter. The first circuit generates a threshold signal. The first comparator is coupled to receive a signal representative of a current through a power switch. Besides, the first comparator generates a control signal in response to the signal and the threshold signal. A frequency of the switching signal is increased in response to the enabling of the control signal. | 12-24-2009 |
20110062876 | OFFLINE LED DRIVING CIRCUITS - An offline LED driving circuit includes a controller, a shunt regulator, an opto-coupler, and a dimming circuit. The controller generates a switching signal to switch a transformer for providing an output voltage and an output current. The shunt regulator is coupled to an output terminal of the LED driving circuit for providing a feedback signal to the controller via the opto-coupler. The dimming circuit coupled to the shunt regulator modulates the feedback signal at a first feedback level and a second feedback level in response to a dimming signal. The output voltage is respectively regulated at a first output level and a second output level in response to the first feedback level and the second feedback level of the feedback signal. The duty cycle of the switching signal will be varied in a soft-start manner when the feedback signal changes from the second feedback level to the first feedback level. | 03-17-2011 |
20110062877 | OFFLINE LED LIGHTING CIRCUIT WITH DIMMING CONTROL - An offline LED lighting circuit comprises a controller and a dimming circuit. The controller generates a switching signal to switch a transformer for generating an output voltage and an output current at an output terminal of the offline LED lighting circuit to drive LEDs. The dimming circuit is coupled to the controller to modulate the switching signal in response to a dimming signal. A first reference voltage and a second reference voltage of the controller are generated in response to the dimming signal. The switching signal is modulated by the first reference voltage and the second reference voltage. The controller regulates the output voltage at a first output level and a second output level in response to both the first reference voltage and the second reference voltage. The second output level is lower than the first output level. | 03-17-2011 |
20120106205 | POWER SUPPLY WITH OPEN-LOOP PROTECTION AND SHORT-CIRCUIT PROTECTION - The power supply according to the present invention comprises a transformer, a power switch, a signal generating circuit, an on-time detection circuit, and a delay circuit. The transformer receives an input voltage and generates an output voltage. The power switch switches the transformer for regulating the output voltage. The signal generating circuit generates a switching signal for controlling switching of the power switch. The on-time detection circuit detects an on-time of the power switch and generates a short-circuit signal. The delay circuit counts to a first delay time or to a second delay time in response to a feedback signal of the power supply and the short-circuit signal to generate a turn off signal for controlling the signal generating circuit to latch the switching signal. | 05-03-2012 |
20130235627 | START-UP CIRCUIT TO DISCHARGE EMI FILTER FOR POWER SAVING OF POWER SUPPLIES - A start-up circuit to discharge EMI filter is developed for power saving. It includes a detection circuit detecting a power source for generating a sample signal. A sample circuit is coupled to the detection circuit for generating a reset signal in response to the sample signal. The reset signal is utilized for discharging a stored voltage of the EMI filter. | 09-12-2013 |
Patent application number | Description | Published |
20080309311 | Power Converter for Compensating a maximum Output Power - A power converter for compensating a maximum output power includes a power switch, a control circuit, an oscillator and a frequency modulator. The control circuit generates a PWM signal in response to the pulse signal generated by the oscillator. The frequency modulator generates a second discharge signal to the oscillator for controlling the maximum output power of the power converter. The second discharge signal is decreased for prolonging a switching period of the PWM signal under a high-line voltage of the power converter. | 12-18-2008 |
20080309312 | Power Converter for Compensating a Maximum Output Power - A power converter and a PWM controller for compensating a maximum output power includes a power switch, an oscillator, a control circuit and a delay modulator. The oscillator generates a pulse signal. The control circuit is coupled to the oscillator for generating a PWM signal and an over current signal in response to the pulse signal and a current sense signal of the power converter. The delay modulator is coupled to the control circuit for generating a delay control signal in response to the PWM signal and the over current signal, wherein the delay control signal is used to prolong a propagation delay time of the control circuit in response to the on-time of the PWM signal, and the propagation delay time can be compensated by the on-time of the PWM signal to limit the maximum output power under a high-line input voltage and a heavy-load condition. | 12-18-2008 |
20080310193 | PWM Controller for Compensating a Maximum Output Power of a Power Converter - A PWM controller having an oscillator, a control circuit and a two-level limiter is provided. The oscillator generates a pulse signal. The control circuit couples to the oscillator for generating a PWM signal in response to the pulse signal, wherein the PWM signal controls a power switch. The two-level limiter couples to the control circuit for generating a two-level limit signal in response to an on-time of the PWM signal, wherein the two-level limit signal is formed by a first-level signal and a second-level signal during a switching period of the PWM signal, and the first-level signal is used to limit the maximum output power of the power converter under a high-line input voltage with a heavy-load condition, and the second-level signal is used to limit the maximum output power of the power converter under a low-line input voltage with the heavy-load condition. | 12-18-2008 |
20100309694 | Start-up Circuit to Discharge EMI Filter for Power Saving of Power Supplies - A start-up circuit to discharge EMI filter is developed for power saving. It includes a detection circuit detecting a power source for generating a sample signal. A sample circuit is coupled to the detection circuit for generating a reset signal in response to the sample signal. The reset signal is utilized for discharging a stored voltage of the EMI filter. | 12-09-2010 |