Patents by Inventor Li Di
Li Di 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).
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Patent number: 11139744Abstract: A flyback power converter includes a primary side controller circuit for controlling a primary side switch; and a secondary side controller circuit for generating an SR (Synchronous Rectification) signal to control an SR switch. The SR signal includes an SR pulse and a ZVS (Zero Voltage Switching) pulse. The SR pulse controls the SR switch for synchronous rectification at the secondary side. The secondary side controller circuit samples and holds a voltage at a first end of the SR switch as a first voltage at a timing between the end of the ZVS pulse and the beginning of the SR pulse, and determines a length of the ZVS pulse so as to control the SR switch to be conductive for a ZVS time period, whereby the primary side switch achieves ZVS. The first voltage is proportional to an input voltage.Type: GrantFiled: June 1, 2020Date of Patent: October 5, 2021Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Wei-Hsu Chang, Ta-Yung Yang, Yu-Chang Chen, Chao-Chi Chen, Chuh-Ching Li, Li-Di Lo, Hao-Wen Chung
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Patent number: 11139742Abstract: A switching controller circuit for controlling a flyback power converter includes: a power transformer, a primary side controller circuit and a secondary side controller circuit. The power transformer is coupled between the input voltage and the output voltage in an isolated manner. The primary side controller circuit controls a primary side switch of the flyback power converter. The secondary side controller circuit generates a synchronous rectification (SR) signal, to control an SR switch of the flyback power converter. The SR signal includes an SR pulse and a soft switching (SS) pulse. The SR pulse controls the SR switch to be ON for an SR period, to achieve synchronous rectification at the secondary side. The SS pulse controls the SR switch to be ON for an SS period, to achieve soft switching of the primary side switch.Type: GrantFiled: May 20, 2020Date of Patent: October 5, 2021Inventors: Wei-Hsu Chang, Ta-Yung Yang, Yu-Chang Chen, Chao-Chi Chen, Chuh-Ching Li, Li-Di Lo, Hao-Wen Chung
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Publication number: 20210126543Abstract: A switching controller circuit for controlling a flyback power converter includes: a power transformer, a primary side controller circuit and a secondary side controller circuit. The power transformer is coupled between the input voltage and the output voltage in an isolated manner. The primary side controller circuit controls a primary side switch of the flyback power converter. The secondary side controller circuit generates a synchronous rectification (SR) signal, to control an SR switch of the flyback power converter. The SR signal includes an SR pulse and a soft switching (SS) pulse. The SR pulse controls the SR switch to be ON for an SR period, to achieve synchronous rectification at the secondary side. The SS pulse controls the SR switch to be ON for an SS period, to achieve soft switching of the primary side switch.Type: ApplicationFiled: May 20, 2020Publication date: April 29, 2021Inventors: Wei-Hsu Chang, Ta-Yung Yang, Yu-Chang Chen, Chao-Chi Chen, Chuh-Ching Li, Li-Di Lo, Hao-Wen Chung
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Publication number: 20210111634Abstract: A flyback power converter includes a primary side controller circuit for controlling a primary side switch; and a secondary side controller circuit for generating an SR (Synchronous Rectification) signal to control an SR switch. The SR signal includes an SR pulse and a ZVS (Zero Voltage Switching) pulse. The SR pulse controls the SR switch for synchronous rectification at the secondary side. The secondary side controller circuit samples and holds a voltage at a first end of the SR switch as a first voltage at a timing between the end of the ZVS pulse and the beginning of the SR pulse, and determines a length of the ZVS pulse so as to control the SR switch to be conductive for a ZVS time period, whereby the primary side switch achieves ZVS. The first voltage is proportional to an input voltage.Type: ApplicationFiled: June 1, 2020Publication date: April 15, 2021Inventors: Wei-Hsu Chang, Ta-Yung Yang, Yu-Chang Chen, Chao-Chi Chen, Chuh-Ching Li, Li-Di Lo, Hao-Wen Chung
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Patent number: 10715028Abstract: A ZVS (zero voltage switching) control circuit for controlling a flyback power converter includes: a primary side controller circuit for generating a switching signal, to control a primary side switch; and a secondary side controller circuit for generating a synchronous rectifier (SR) control signal for controlling a synchronous rectifier switch. The SR control signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the synchronous rectifier switch to perform secondary side synchronous rectification. The secondary side controller circuit determines a trigger timing point of the ZVS pulse according to a waveform characteristic of a ringing signal, to control the synchronous rectifier switch to be ON for a predetermined period, thereby achieving zero voltage switching of the primary side switch. The primary side or the secondary side controller circuit includes a jitter controller for performing jitter control on the ZVS pulse.Type: GrantFiled: September 28, 2019Date of Patent: July 14, 2020Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Tzu-Chen Lin, Kun-Yu Lin, Li-Di Lo, Wei-Hsu Chang
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Patent number: 10686383Abstract: 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: GrantFiled: August 15, 2019Date of Patent: June 16, 2020Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Li-Di Lo, Chien-Fu Tang, Isaac Y. Chen
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Publication number: 20200153327Abstract: A ZVS (zero voltage switching) control circuit for controlling a flyback power converter includes: a primary side controller circuit for generating a switching signal, to control a primary side switch; and a secondary side controller circuit for generating a synchronous rectifier (SR) control signal for controlling a synchronous rectifier switch. The SR control signal includes an SR-control pulse and a ZVS pulse. The SR-control pulse controls the synchronous rectifier switch to perform secondary side synchronous rectification. The secondary side controller circuit determines a trigger timing point of the ZVS pulse according to a waveform characteristic of a ringing signal, to control the synchronous rectifier switch to be ON for a predetermined period, thereby achieving zero voltage switching of the primary side switch. The primary side or the secondary side controller circuit includes a jitter controller for performing jitter control on the ZVS pulse.Type: ApplicationFiled: September 28, 2019Publication date: May 14, 2020Inventors: Tzu-Chen Lin, Kun-Yu Lin, Li-Di Lo, Wei-Hsu Chang
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Publication number: 20200099307Abstract: 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: ApplicationFiled: August 15, 2019Publication date: March 26, 2020Inventors: Li-Di Lo, Chien-Fu Tang, Isaac Y. Chen
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Patent number: 10566893Abstract: A ZVS (zero voltage switching) control circuit for use in a flyback power converter includes a primary side controller circuit, a secondary side controller circuit, and a pulse transformer. In one switching cycle, a synchronous rectifier transistor is turned ON twice to generate a circulation current at the primary side winding, and after the synchronous rectifier transistor is turned OFF, the power transistor is turned ON for zero voltage switching. A synchronous signal coupled between the primary side and the secondary side is employed to synchronize the power transistor and the synchronous transistor. The synchronous signal also triggers an SR-ZVS pulse to turn ON the synchronous rectifier transistor for achieving the zero voltage switching when the power transistor is turned ON.Type: GrantFiled: September 18, 2018Date of Patent: February 18, 2020Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Ta-Yung Yang, Tzu-Chen Lin, Li-Di Luo, Pei-Sheng Tsu
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Patent number: 10326351Abstract: 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: GrantFiled: September 6, 2018Date of Patent: June 18, 2019Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Li-Di Lo, Isaac Y. Chen, Chien-Fu Tang
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Publication number: 20190149032Abstract: A ZVS (zero voltage switching) control circuit for use in a flyback power converter includes a primary side controller circuit, a secondary side controller circuit, and a pulse transformer. In one switching cycle, a synchronous rectifier transistor is turned ON twice to generate a circulation current at the primary side winding, and after the synchronous rectifier transistor is turned OFF, the power transistor is turned ON for zero voltage switching. A synchronous signal coupled between the primary side and the secondary side is employed to synchronize the power transistor and the synchronous transistor. The synchronous signal also triggers an SR-ZVS pulse to turn ON the synchronous rectifier transistor for achieving the zero voltage switching when the power transistor is turned ON.Type: ApplicationFiled: September 18, 2018Publication date: May 16, 2019Inventors: Ta-Yung Yang, Tzu-Chen Lin, Li-Di Luo, Pei-Sheng Tsu
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Publication number: 20190140534Abstract: 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: ApplicationFiled: September 6, 2018Publication date: May 9, 2019Inventors: Li-Di Lo, Isaac Y. Chen, Chien-Fu Tang
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Patent number: 10014786Abstract: A flyback power converter includes a transformer, a power switch, a power switch control circuit, a synchronous rectification (SR) switch, an SR switch control circuit, and a signal coupler circuit. The signal coupler circuit includes a primary port and a secondary port, wherein the primary port is electrically connected to the power switch control circuit, and the secondary port is electrically connected to the SR switch control circuit. The primary port and the secondary port receive different signals generated by the power switch control circuit and the SR switch control circuit respectively, and the signal coupler circuit senses and converts the different signals to generate corresponding converted signals at the secondary port and the primary port respectively in different and non-overlapping time periods, without direct contact or direct connection between the primary side and the secondary side of the transformer.Type: GrantFiled: November 10, 2017Date of Patent: July 3, 2018Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Ta-Yung Yang, Tzu-Chen Lin, Bing Zeng, Li-Di Luo
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Publication number: 20180138818Abstract: A flyback power converter includes a transformer, a power switch, a power switch control circuit, a synchronous rectification (SR) switch, an SR switch control circuit, and a signal coupler circuit. The signal coupler circuit includes a primary port and a secondary port, wherein the primary port is electrically connected to the power switch control circuit, and the secondary port is electrically connected to the SR switch control circuit. The primary port and the secondary port receive different signals generated by the power switch control circuit and the SR switch control circuit respectively, and the signal coupler circuit senses and converts the different signals to generate corresponding converted signals at the secondary port and the primary port respectively in different and non-overlapping time periods, without direct contact or direct connection between the primary side and the secondary side of the transformer.Type: ApplicationFiled: November 10, 2017Publication date: May 17, 2018Inventors: Ta-Yung Yang, Tzu-Chen Lin, Bing Zeng, Li-Di Luo
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Patent number: 9755530Abstract: The present invention discloses a power converter with synchronous control function and control method thereof. The power converter includes: a transformer, a power switch, a switch control unit, a signal coupling circuit, a synchronous rectifying switch and a secondary side control circuit. The switch control unit generates an operation signal according to a feedback signal, and generates a first synchronous signal which is related to the operation signal. The signal coupling circuit couples the first synchronous signal to generate a second synchronous signal. The synchronous rectifying switch is turned ON/OFF according to a synchronous rectifying switch signal, for synchronous rectification. The secondary side control circuit generates the synchronous rectifying switch signal according to a secondary side level detection signal and the second synchronous signal, to control the synchronous rectifying switch. The ON time of the power switch and the ON time of the synchronous rectifying switch do not overlap.Type: GrantFiled: May 2, 2016Date of Patent: September 5, 2017Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Li-Di Luo, Yu-Kai Chen, Yu-Chang Chen
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Patent number: 9755529Abstract: The present invention provides a flyback power converter and a control circuit thereof. The flyback power converter includes a transformer, a power switch, a driver, a synchronous rectification (SR) switch, a controller, and a signal coupler circuit. The transformer has a primary winding and a secondary winding. The power switch controls the conduction time of the primary winding; and the SR switch controls the conduction time of the secondary winding. The controller controls the SR switch and generates an ON pulse signal and an OFF pulse signal in a normal operation mode. When an output voltage reaches a lower limit voltage, the flyback power converter operates in the normal operation mode. The driver generates a switching signal according to the ON pulse signal and the OFF pulse signal in the normal operation mode, to determine a start conduction time point and an end conduction time point of the primary winding.Type: GrantFiled: May 5, 2016Date of Patent: September 5, 2017Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Yu-Chang Chen, Li-Di Luo, Tzu-Chen Lin
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Patent number: 9601983Abstract: The present invention provides a flyback power converter and a control circuit and a control method thereof. The flyback power converter includes: a power stage circuit, a voltage sense circuit, a current sense circuit, and a control circuit. When the flyback power converter operates in a quasi-resonant mode, the control circuit determines a time point of turning OFF a power switch in the power stage circuit according to a current sense signal, a pulse width modulation (PWM) frequency of a PWM signal, and a predetermined threshold, wherein the control circuit adaptively adjusts an ON period of the power switch, or adaptively adjusts an operation bandwidth or an amplifier gain of an error amplifier circuit in a feedback control loop according to the PWM frequency to mitigate an output voltage ripple.Type: GrantFiled: April 20, 2015Date of Patent: March 21, 2017Assignee: RICHTEK TECHNOLOGY CORPORATIONInventors: Kuang-Fu Chang, Tzu-Chen Lin, Li-Di Luo
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Publication number: 20160344296Abstract: The present invention discloses a power converter with synchronous control function and control method thereof. The power converter includes: a transformer, a power switch, a switch control unit, a signal coupling circuit, a synchronous rectifying switch and a secondary side control circuit. The switch control unit generates an operation signal according to a feedback signal, and generates a first synchronous signal which is related to the operation signal. The signal coupling circuit couples the first synchronous signal to generate a second synchronous signal. The synchronous rectifying switch is turned ON/OFF according to a synchronous rectifying switch signal, for synchronous rectification. The secondary side control circuit generates the synchronous rectifying switch signal according to a secondary side level detection signal and the second synchronous signal, to control the synchronous rectifying switch. The ON time of the power switch and the ON time of the synchronous rectifying switch do not overlap.Type: ApplicationFiled: May 2, 2016Publication date: November 24, 2016Inventors: Li-Di Luo, Yu-Kai Chen, Yu-Chang Chen
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Publication number: 20160329819Abstract: The present invention provides a flyback power converter and a control circuit thereof. The flyback power converter includes a transformer, a power switch, a driver, a synchronous rectification (SR) switch, a controller, and a signal coupler circuit. The transformer has a primary winding and a secondary winding. The power switch controls the conduction time of the primary winding; and the SR switch controls the conduction time of the secondary winding. The controller controls the SR switch and generates an ON pulse signal and an OFF pulse signal in a normal operation mode. When an output voltage reaches a lower limit voltage, the flyback power converter operates in the normal operation mode. The driver generates a switching signal according to the ON pulse signal and the OFF pulse signal in the normal operation mode, to determine a start conduction time point and an end conduction time point of the primary winding.Type: ApplicationFiled: May 5, 2016Publication date: November 10, 2016Inventors: Yu-Chang Chen, Li-Di Luo, Tzu-Chen Lin
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Publication number: 20150311778Abstract: The present invention provides a flyback power converter and a control circuit and a control method thereof. The flyback power converter includes: a power stage circuit, a voltage sense circuit, a current sense circuit, and a control circuit. When the flyback power converter operates in a quasi-resonant mode, the control circuit determines a time point of turning OFF a power switch in the power stage circuit according to a current sense signal, a pulse width modulation (PWM) frequency of a PWM signal, and a predetermined threshold, wherein the control circuit adaptively adjusts an ON period of the power switch, or adaptively adjusts an operation bandwidth or an amplifier gain of an error amplifier circuit in a feedback control loop according to the PWM frequency to mitigate an output voltage ripple.Type: ApplicationFiled: April 20, 2015Publication date: October 29, 2015Applicant: RICHTEK TECHNOLOGY CORPORATIONInventors: Kuang-Fu Chang, Tzu-Chen Lin, Li-Di Luo