Patents by Inventor Chien-Fu Tang

Chien-Fu Tang 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).

  • Patent number: 11169179
    Abstract: A current sensing circuit having self-calibration includes two leads, a sensing element having a sensing resistance, and a sensing and calibration circuit. The sensing and calibration circuit senses and calibrates a sensing voltage of the sensing element, and senses a sensing current through the sensing element according to the sensing resistance and the sensing voltage, to generate a current sensing output signal. The sensing and calibration circuit includes two pads, a V2I circuit, a current mirror circuit and an I2V circuit. The sensing element has a first temperature coefficient (TC). The TC and/or the resistance of an adjusting resistor in the V2I circuit and an adjusting resistor in the I2V circuit are determined according to the first TC, such that the TC of the current sensing output signal is equal to 0.
    Type: Grant
    Filed: December 8, 2020
    Date of Patent: November 9, 2021
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Isaac Y. Chen, Chien-Fu Tang, Hsin-Yi Wu, Kai-Chuan Chan, Yu-Lin Yang
  • Publication number: 20210270870
    Abstract: A current sensing circuit having self-calibration includes two leads, a sensing element having a sensing resistance, and a sensing and calibration circuit. The sensing and calibration circuit senses and calibrates a sensing voltage of the sensing element, and senses a sensing current through the sensing element according to the sensing resistance and the sensing voltage, to generate a current sensing output signal. The sensing and calibration circuit includes two pads, a V2I circuit, a current mirror circuit and an I2V circuit. The sensing element has a first temperature coefficient (TC). The TC and/or the resistance of an adjusting resistor in the V2I circuit and an adjusting resistor in the I2V circuit are determined according to the first TC, such that the TC of the current sensing output signal is equal to 0.
    Type: Application
    Filed: December 8, 2020
    Publication date: September 2, 2021
    Inventors: Isaac Y. Chen, Chien-Fu Tang, Hsin-Yi Wu, Kai-Chuan Chan, Yu-Lin Yang
  • Publication number: 20210167691
    Abstract: A low delay time power converter circuit includes a driver circuit and a load. The driver circuit generates a switching driving signal to control the load. The driver circuit includes a switching control circuit and an output stage circuit which includes a first power switch, a second power switch and an impedance adjusting circuit. When the switching control circuit controls the switching driving signal to a first voltage level at a first time point, the first power switch is turned ON and then is turned OFF after a predetermined period. When the switching control circuit controls the switching driving signal to a second voltage level at a second time point, the second power switch is turned ON. The time point when the first power switch is turned OFF is earlier than the second time point. A resistance of the impedance adjusting circuit is larger than a conductive resistance of the first power switch.
    Type: Application
    Filed: July 12, 2020
    Publication date: June 3, 2021
    Inventors: Isaac Y. Chen, Chien-Fu Tang, Jo-Yu Wang
  • Patent number: 10686383
    Abstract: Whether a synchronous signal includes a synchronous pulse is determined by detecting whether there is a positive pulse higher than a positive threshold followed by a negative pulse lower than a negative threshold. The pulse signal detection method includes: comparing the synchronous signal with the positive threshold; comparing the synchronous signal with the negative threshold; and determining that the synchronous pulse exists when the positive pulse of the synchronous signal is higher than the positive threshold and the negative pulse of the synchronous signal is lower than the negative threshold in a post detection period after the positive pulse of the synchronous signal is determined higher than the positive threshold.
    Type: Grant
    Filed: August 15, 2019
    Date of Patent: June 16, 2020
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Li-Di Lo, Chien-Fu Tang, Isaac Y. Chen
  • Publication number: 20200099307
    Abstract: Whether a synchronous signal includes a synchronous pulse is determined by detecting whether there is a positive pulse higher than a positive threshold followed by a negative pulse lower than a negative threshold. The pulse signal detection method includes: comparing the synchronous signal with the positive threshold; comparing the synchronous signal with the negative threshold; and determining that the synchronous pulse exists when the positive pulse of the synchronous signal is higher than the positive threshold and the negative pulse of the synchronous signal is lower than the negative threshold in a post detection period after the positive pulse of the synchronous signal is determined higher than the positive threshold.
    Type: Application
    Filed: August 15, 2019
    Publication date: March 26, 2020
    Inventors: Li-Di Lo, Chien-Fu Tang, Isaac Y. Chen
  • Patent number: 10560012
    Abstract: A ZVS (zero voltage switching) control circuit for use in a flyback power converter includes a primary side controller and a secondary side controller. The primary side controller generates a switching signal to control a power transformer through a power transistor to generate an output voltage. The secondary side controller generates an SR (synchronous rectifier) signal to control an SR transistor at a secondary side of the power transformer. The SR signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the SR transistor according to a demagnetizing period of the power transformer. The ZVS pulse determines the starting timing of the switching signal to achieve zero voltage switching for the power transistor. The secondary side controller generates the ZVS pulse after a delay time from when the power transformer is demagnetized. The delay time is determined according to an output load of the output voltage.
    Type: Grant
    Filed: January 14, 2019
    Date of Patent: February 11, 2020
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Ta-Yung Yang, Tzu-Chen Lin, Chien-Fu Tang
  • Publication number: 20200036280
    Abstract: A ZVS (zero voltage switching) control circuit for use in a flyback power converter includes a primary side controller and a secondary side controller. The primary side controller generates a switching signal to control a power transformer through a power transistor to generate an output voltage. The secondary side controller generates an SR (synchronous rectifier) signal to control an SR transistor at a secondary side of the power transformer. The SR signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the SR transistor according to a demagnetizing period of the power transformer. The ZVS pulse determines the starting timing of the switching signal to achieve zero voltage switching for the power transistor. The secondary side controller generates the ZVS pulse after a delay time from when the power transformer is demagnetized. The delay time is determined according to an output load of the output voltage.
    Type: Application
    Filed: January 14, 2019
    Publication date: January 30, 2020
    Inventors: Ta-Yung Yang, Tzu-Chen Lin, Chien-Fu Tang
  • Patent number: 10505464
    Abstract: A discrete-time current sense circuit includes: a current mirror circuit, which includes: a power switch, for providing the communication current; and a sampling switch, which is for sampling the communication protocol current in a sampling period in a discrete manner, to generate a sampling current; a bias circuit, for providing a reference voltage to the reference node in the sampling period according to a communication protocol voltage of the communication protocol voltage node; a signal conversion circuit, for generating the discrete-time current sense signal according to the sampling current; and a first switch, for operating to determine the sampling period; wherein the sampling period is part of a complete period in which the power switch provides the communication protocol current.
    Type: Grant
    Filed: December 13, 2018
    Date of Patent: December 10, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Chien-Fu Tang, Hsin-Yi Wu, Isaac Y. Chen
  • Patent number: 10461652
    Abstract: A flyback power converter includes: a transformer, a power switch, a switch control unit, a synchronous rectifier switch and a secondary side control circuit. The secondary side control circuit includes: a switch signal generation circuit and a first power conversion circuit. The secondary side control circuit is coupled to the synchronous rectifier switch and the secondary winding of the transformer. The switch signal generation circuit generates the synchronous rectifier switch signal selectively according to a first power or a second power, to control the synchronous rectifier switch. The first power is related to the output voltage. The first power conversion circuit generates the second power according to a secondary phase signal on a phase node between the secondary winding of the transformer and the synchronous rectifier switch.
    Type: Grant
    Filed: September 15, 2018
    Date of Patent: October 29, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Chien-Fu Tang, Jo-Yu Wang, Isaac Y. Chen
  • Patent number: 10461624
    Abstract: The present invention provides a power switch control circuit and an open detection method thereof. The power switch control circuit is for generating an operation signal at an operation signal output pin according to an input signal, wherein the operation signal is for operating a power switch. The power switch control circuit includes: a current injection circuit, which is connected to the operation signal output pin, and provides a predetermined current to the operation signal output pin according to an enable signal; and an open detection circuit, which is coupled to the current injection circuit, and determines whether a connection between the operation signal output pin and the power switch is open according to a level of the operation signal output pin at a detection time point or according to a level variation of the operation signal output pin during a detection time period, whereby an open detection signal is generated.
    Type: Grant
    Filed: April 11, 2017
    Date of Patent: October 29, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Pei-Sheng Tsu, Chien-Fu Tang, Isaac Y. Chen
  • Publication number: 20190296651
    Abstract: A discrete-time current sense circuit includes: a current mirror circuit, which includes: a power switch, for providing the communication current; and a sampling switch, which is for sampling the communication protocol current in a sampling period in a discrete manner, to generate a sampling current; a bias circuit, for providing a reference voltage to the reference node in the sampling period according to a communication protocol voltage of the communication protocol voltage node; a signal conversion circuit, for generating the discrete-time current sense signal according to the sampling current; and a first switch, for operating to determine the sampling period; wherein the sampling period is part of a complete period in which the power switch provides the communication protocol current.
    Type: Application
    Filed: December 13, 2018
    Publication date: September 26, 2019
    Inventors: Chien-Fu Tang, Hsin-Yi Wu, Isaac Y. Chen
  • Patent number: 10355612
    Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.
    Type: Grant
    Filed: January 8, 2018
    Date of Patent: July 16, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Chien-Fu Tang, Su-Yuan Lin, Yi-Wei Lee, Isaac Y. Chen
  • Patent number: 10326351
    Abstract: A switching regulator includes: a controller power ON reset (POR) circuit, a controller post-POR signal generation circuit, and a pulse width modulation (PWM) signal generation circuit. The controller post-POR signal generation circuit switches the controller post-POR signal to a ready level after a controller pre-POR signal is switched to a controller reset-accomplished level and a driver signal starts switching levels to operate a power switch. The PWM signal generation circuit sets a duty ratio of a PWM signal to a predetermined minimum duty ratio after the controller pre-POR signal is switched to the controller reset-accomplished level and before the controller post-POR signal is switched to a ready level.
    Type: Grant
    Filed: September 6, 2018
    Date of Patent: June 18, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Li-Di Lo, Isaac Y. Chen, Chien-Fu Tang
  • Patent number: 10291137
    Abstract: A flyback power converter includes a transformer having an auxiliary winding for generating an auxiliary voltage and providing a supply voltage on a supply node; a primary side controller circuit which is powered by the supply voltage from the supply node; and a high voltage (HV) start-up circuit. The HV start-up circuit is coupled to an high voltage signal through a HV input terminal and generates the supply voltage through a supply output terminal, wherein when the supply voltage does not exceed a start-up voltage threshold, a HV start-up switch conducts the HV input terminal and the supply output terminal to provide the supply voltage, and when the supply voltage exceeds a start-up voltage threshold, the HV start-up switch is OFF. The HV start-up circuit and the primary side controller circuit are packaged in two separate integrated circuit packages respectively.
    Type: Grant
    Filed: July 19, 2018
    Date of Patent: May 14, 2019
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Chien-Fu Tang, Isaac Y. Chen, Tzu-Chen Lin, Kun-Yu Lin, Li-Yang Hsiao, Yung-Chih Lai
  • Publication number: 20190140534
    Abstract: A switching regulator includes: a controller power ON reset (POR) circuit, a controller post-POR signal generation circuit, and a pulse width modulation (PWM) signal generation circuit. The controller post-POR signal generation circuit switches the controller post-POR signal to a ready level after a controller pre-POR signal is switched to a controller reset-accomplished level and a driver signal starts switching levels to operate a power switch. The PWM signal generation circuit sets a duty ratio of a PWM signal to a predetermined minimum duty ratio after the controller pre-POR signal is switched to the controller reset-accomplished level and before the controller post-POR signal is switched to a ready level.
    Type: Application
    Filed: September 6, 2018
    Publication date: May 9, 2019
    Inventors: Li-Di Lo, Isaac Y. Chen, Chien-Fu Tang
  • Publication number: 20190115844
    Abstract: A flyback power converter includes: a transformer, a power switch, a switch control unit, a synchronous rectifier switch and a secondary side control circuit. The secondary side control circuit includes: a switch signal generation circuit and a first power conversion circuit. The secondary side control circuit is coupled to the synchronous rectifier switch and the secondary winding of the transformer. The switch signal generation circuit generates the synchronous rectifier switch signal selectively according to a first power or a second power, to control the synchronous rectifier switch. The first power is related to the output voltage. The first power conversion circuit generates the second power according to a secondary phase signal on a phase node between the secondary winding of the transformer and the synchronous rectifier switch.
    Type: Application
    Filed: September 15, 2018
    Publication date: April 18, 2019
    Inventors: Chien-Fu Tang, Jo-Yu Wang, Isaac Y. Chen
  • Publication number: 20190028033
    Abstract: A flyback power converter includes a transformer having an auxiliary winding for generating an auxiliary voltage and providing a supply voltage on a supply node; a primary side controller circuit which is powered by the supply voltage from the supply node; and a high voltage (HV) start-up circuit. The HV start-up circuit is coupled to an high voltage signal through a HV input terminal and generates the supply voltage through a supply output terminal, wherein when the supply voltage does not exceed a start-up voltage threshold, a HV start-up switch conducts the HV input terminal and the supply output terminal to provide the supply voltage, and when the supply voltage exceeds a start-up voltage threshold, the HV start-up switch is OFF. The HV start-up circuit and the primary side controller circuit are packaged in two separate integrated circuit packages respectively.
    Type: Application
    Filed: July 19, 2018
    Publication date: January 24, 2019
    Inventors: Chien-Fu Tang, Isaac Y. Chen, Tzu-Chen Lin, Kun-Yu Lin, Li-Yang Hsiao, Yung-Chih Lai
  • Patent number: 10153703
    Abstract: The present invention provides a flyback power converter with a programmable output and a control circuit and a control method thereof. The flyback power converter converts an input voltage to a programmable output voltage according to a setting signal, wherein the programmable output voltage switches between different levels. The flyback power converter includes: a transformer circuit, a power switch circuit, a current sense circuit, an opto-coupler circuit, and a control circuit. The control circuit adaptively adjusts an operation signal according to a level of the programmable output voltage, to maintain a same or relatively higher operation frequency of the operation signal when the programmable output voltage switches to a relatively lower level, so as to maintain a phase margin while supplying the same output current.
    Type: Grant
    Filed: February 15, 2017
    Date of Patent: December 11, 2018
    Assignee: RICHTEK TECHNOLOGY CORPORATION
    Inventors: Kuang-Fu Chang, Tzu-Chen Lin, Chien-Fu Tang
  • Publication number: 20180212528
    Abstract: A flyback power converter circuit converting an input voltage to an output voltage includes a transformer, a power switch, a synchronous rectifier (SR) switch, and a secondary side control circuit. The secondary side control circuit controls the SR switch to be ON when the power switch is OFF. The secondary side control circuit includes a driving switch for controlling the SR switch, a synchronous control circuit powered by a voltage related to the output voltage, which controls the driving switch to operate the SR switch, and a clamping circuit including a clamping switch and a clamping switch control circuit. The clamping switch control circuit controls the clamping switch according to a current inflow terminal voltage of the clamping switch and/or the voltage related to the output voltage, such that, during a secondary side power-on period, an equivalent impedance of the current inflow terminal of the clamping switch is smaller than a predetermined clamping impedance.
    Type: Application
    Filed: January 8, 2018
    Publication date: July 26, 2018
    Inventors: Chien-Fu Tang, Su-Yuan Lin, Yi-Wei Lee, Isaac Y. Chen
  • Publication number: 20180138797
    Abstract: The present invention provides a power switch control circuit and an open detection method thereof. The power switch control circuit is for generating an operation signal at an operation signal output pin according to an input signal, wherein the operation signal is for operating a power switch. The power switch control circuit includes: a current injection circuit, which is connected to the operation signal output pin, and provides a predetermined current to the operation signal output pin according to an enable signal; and an open detection circuit, which is coupled to the current injection circuit, and determines whether a connection between the operation signal output pin and the power switch is open according to a level of the operation signal output pin at a detection time point or according to a level variation of the operation signal output pin during a detection time period, whereby an open detection signal is generated.
    Type: Application
    Filed: April 11, 2017
    Publication date: May 17, 2018
    Inventors: Pei-Sheng Tsu, Chien-Fu Tang, Isaac Y. Chen