Patents by Inventor Cheng-Hsuan Fan

Cheng-Hsuan Fan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20130229833
    Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.
    Type: Application
    Filed: April 18, 2013
    Publication date: September 5, 2013
    Applicant: RICHTEK TECHNOLOGY CORP.
    Inventors: Liang-Pin TAI, Tzu-Chen LIN, Cheng-Hsuan FAN
  • Patent number: 8503196
    Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.
    Type: Grant
    Filed: July 19, 2010
    Date of Patent: August 6, 2013
    Assignee: Richtek Technology Corp.
    Inventors: Liang-Pin Tai, Tzu-Chen Lin, Cheng-Hsuan Fan
  • Patent number: 8373404
    Abstract: A flyback voltage converter includes a transformer having a primary winding and a secondary winding, a switch serially connected to the primary winding for being switched to produce a current in the secondary winding, and a negative lock loop to adjust the peak value of the current in the secondary winding according to a current conduction time during which the current in the secondary winding is higher than a current threshold, such that the peak value of the current in the secondary winding will be in inverse proportion to the time.
    Type: Grant
    Filed: November 6, 2009
    Date of Patent: February 12, 2013
    Assignee: Richtek Technology Corp.
    Inventors: Chao-Hsuan Chuang, Ching-Hsiang Yang, Cheng-Hsuan Fan, Hung-Che Chou
  • Patent number: 8000071
    Abstract: An apparatus and method for reducing the die area of a PWM controller include a protection circuit triggered by a fault index signal for counting, and the counting time is provided for a delay time required by fault verification. Therefore, fault detection circuits can be eliminated and the purpose of reducing the die area can be achieved.
    Type: Grant
    Filed: May 29, 2008
    Date of Patent: August 16, 2011
    Assignee: Richtek Technology Corp.
    Inventors: Pei-Lun Huang, Cheng-Hsuan Fan
  • Patent number: 7991172
    Abstract: The present invention discloses a half-voltage headphone driver circuit, comprising: at least one operational amplifier providing an output to a headphone speaker, and a charge pump receiving a supply voltage (VDD), generating a positive half-voltage and a negative half-voltage (VDD/2 and ?VDD/2) based on the supply voltage, and supplying the positive half-voltage and negative half-voltage as high and low operation levels to the at least one operational amplifier.
    Type: Grant
    Filed: May 31, 2007
    Date of Patent: August 2, 2011
    Assignee: Richtek Technology Corporation
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Shui-Mu Lin, Chih-Ping Tan
  • Patent number: 7907377
    Abstract: For protecting a power system, two or three of over current, thermal and under voltage protection circuits are integrated as one protection circuit but operate independently, and one or more protection points thereof are adjusted dynamically in response to detected condition of the power system. Specifically, using voltage and current conditions in the power system to modify the over current protection and the thermal protection maximizes the performance of the power system and covers the process bias in the circuits.
    Type: Grant
    Filed: January 7, 2009
    Date of Patent: March 15, 2011
    Assignee: Richtek Technology Corp.
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Publication number: 20110018590
    Abstract: A feedback circuit for an isolated power converter includes an opto-coupler and a reversed polarity regulator. The opto-coupler provides a current related to an output voltage of the isolated power converter. When the isolated power converter enters light load, the output voltage rises and the reversed polarity regulator reduces the current to decrease the power consumption and thus improve the light load efficiency of the isolated power converter.
    Type: Application
    Filed: July 19, 2010
    Publication date: January 27, 2011
    Applicant: RICHTEK TECHNOLOGY CORP.
    Inventors: LIANG-PIN TAI, TZU-CHEN LIN, CHENG-HSUAN FAN
  • Patent number: 7728571
    Abstract: The present invention discloses a load-dependent frequency jittering circuit, comprising: a load condition detection circuit for receiving a switching signal and generating an output according to a load condition; a number generator for receiving the output of the load condition detection circuit and generating a number; a digital to analog converter for converting the output of the number generator to an analog signal; and an oscillator for generating a jittered frequency according to the output of the digital to analog converter.
    Type: Grant
    Filed: November 6, 2007
    Date of Patent: June 1, 2010
    Assignee: Richtek Technology Corporation, R.O.C.
    Inventors: Chao-Hsuan Chuang, Cheng-Hsuan Fan, Hung-Che Chou, Ching-Hsiang Yang
  • Publication number: 20100117617
    Abstract: A flyback voltage converter includes a transformer having a primary winding and a secondary winding, a switch serially connected to the primary winding for being switched to produce a current in the secondary winding, and a negative lock loop to adjust the peak value of the current in the secondary winding according to a current conduction time during which the current in the secondary winding is higher than a current threshold, such that the peak value of the current in the secondary winding will be in inverse proportion to the time.
    Type: Application
    Filed: November 6, 2009
    Publication date: May 13, 2010
    Inventors: Chao-Hsuan Chuang, Ching-Hsiang Yang, Cheng-Hsuan Fan, Hung-Che Chou
  • Patent number: 7714551
    Abstract: A linear voltage regulator comprises a transistor for converting a supply voltage to an output voltage. By directly monitoring the supply voltage and thereby rapidly responding when the supply voltage suffers a ripple, the linear voltage regulator enhances the stability of the output voltage.
    Type: Grant
    Filed: February 12, 2007
    Date of Patent: May 11, 2010
    Assignee: Richtek Technology Corp.
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Patent number: 7619396
    Abstract: Time-sharing technique is used for power conversion to improve the thermal dissipation thereof. In a power supply arrangement to provide a supply voltage to a load, a plurality of linear regulators are so switched that each time only one of them is enabled to convert an input voltage to the supply voltage, thereby each of them suffering less thermal dissipation.
    Type: Grant
    Filed: September 26, 2006
    Date of Patent: November 17, 2009
    Assignee: Richtek Technology Corp.
    Inventors: Chao-Hsuan Chuang, Cheng-Hsuan Fan, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Patent number: 7609533
    Abstract: A flyback converter has a controller to switch a power switch so as to convert an input voltage to an output voltage for a load by monitoring an output voltage dependent signal and a current sensing signal derived from a current flowing through the power switch, a light-load efficiency improving apparatus monitors the load and a supply voltage provided for the controller to selectively clamp the output voltage dependent signal when the load is lower than a first threshold value and the supply voltage is lower than a second threshold value, so as to increase the supply voltage.
    Type: Grant
    Filed: August 3, 2007
    Date of Patent: October 27, 2009
    Assignee: Richtek Technology Corp.
    Inventors: Chao-Hsuan Chuang, Cheng-Hsuan Fan, Hung-Che Chou
  • Patent number: 7570121
    Abstract: A frequency jittering control circuit wherein by means of the characteristics of a PLL whose input switches between different frequencies, the output frequency of the PLL swings between the different frequencies to achieve the desired frequency jittering.
    Type: Grant
    Filed: June 25, 2007
    Date of Patent: August 4, 2009
    Assignee: Richtek Technology Corporation
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Patent number: 7535690
    Abstract: For protecting a power system, two or three of over current, thermal and under voltage protection circuits are integrated as one protection circuit but operate independently, and one or more protection points thereof are adjusted dynamically in response to detected condition of the power system. Specifically, using voltage and current conditions in the power system to modify the over current protection and the thermal protection maximizes the performance of the power system and covers the process bias in the circuits.
    Type: Grant
    Filed: September 11, 2006
    Date of Patent: May 19, 2009
    Assignee: Richtek Technology Corp.
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Publication number: 20090115391
    Abstract: The present invention discloses a load-dependent frequency jittering circuit, comprising: a load condition detection circuit for receiving a switching signal and generating an output according to a load condition; a number generator for receiving the output of the load condition detection circuit and generating a number; a digital to analog converter for converting the output of the number generator to an analog signal; and an oscillator for generating a jittered frequency according to the output of the digital to analog converter.
    Type: Application
    Filed: November 6, 2007
    Publication date: May 7, 2009
    Inventors: Chao-Hsuan Chuang, Cheng-Hsuan Fan, Hung-Che Chou, Ching-Hsiang Yang
  • Publication number: 20090116160
    Abstract: For protecting a power system, two or three of over current, thermal and under voltage protection circuits are integrated as one protection circuit but operate independently, and one or more protection points thereof are adjusted dynamically in response to detected condition of the power system. Specifically, using voltage and current conditions in the power system to modify the over current protection and the thermal protection maximizes the performance of the power system and covers the process bias in the circuits.
    Type: Application
    Filed: January 7, 2009
    Publication date: May 7, 2009
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Chih-Ping Tan
  • Patent number: 7489182
    Abstract: The present invention discloses a charge pump start up circuit comprising: a start up transistor having one end which is electrically connected with a voltage supply source, and another end which is electrically connected to a voltage node; and a charge pump circuit having an input which is electrically connected with the voltage node, and an output which is electrically with the gate of the start up transistor.
    Type: Grant
    Filed: May 17, 2007
    Date of Patent: February 10, 2009
    Assignee: Richtek Technology Corporation
    Inventors: Hung-Che Chou, Chao-Hsuan Chuang, Cheng-Hsuan Fan, Liang-Pin Tai
  • Publication number: 20080298095
    Abstract: A flyback converter has a controller to switch a power switch so as to convert an input voltage to an output voltage for a load by monitoring an output voltage dependent signal and a current sensing signal derived from a current flowing through the power switch, a light-load efficiency improving apparatus monitors the load and a supply voltage provided for the controller to selectively clamp the output voltage dependent signal when the load is lower than a first threshold value and the supply voltage is lower than a second threshold value, so as to increase the supply voltage.
    Type: Application
    Filed: August 3, 2007
    Publication date: December 4, 2008
    Inventors: Chao-Hsuan Chuang, Cheng-Hsuan Fan, Hung-Che Chou
  • Publication number: 20080298605
    Abstract: The present invention discloses a half-voltage headphone driver circuit, comprising: at least one operational amplifier providing an output to a headphone speaker, and a charge pump receiving a supply voltage (VDD), generating a positive half-voltage and a negative half-voltage (VDD/2 and ?VDD/2) based on the supply voltage, and supplying the positive half-voltage and negative half-voltage as high and low operation levels to the at least one operational amplifier.
    Type: Application
    Filed: May 31, 2007
    Publication date: December 4, 2008
    Inventors: Cheng-Hsuan Fan, Chao-Hsuan Chuang, Hung-Che Chou, Ching-Hsiang Yang, Shui-Mu Lin, Chih-Ping Tan
  • Publication number: 20080298099
    Abstract: An apparatus and method for reducing the die area of a PWM controller include a protection circuit triggered by a fault index signal for counting, and the counting time is provided for a delay time required by fault verification. Therefore, fault detection circuits can be eliminated and the purpose of reducing the die area can be achieved.
    Type: Application
    Filed: May 29, 2008
    Publication date: December 4, 2008
    Inventors: Pei-Lun Huang, Cheng-Hsuan Fan