Patents by Inventor Junming Zhang

Junming Zhang 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: 20150016154
    Abstract: A peak sample circuit for AC voltage, including: a rectifier coupled to receive an AC voltage and to rectify the AC voltage to generate a rectified signal; a delay circuit coupled to receive the rectified signal and to delay the rectified signal to generate a delayed rectified signal; a comparison circuit coupled to receive the delayed rectified signal and to generate a square signal based on the comparison of the rectified signal and the delayed rectified signal; and a sample output circuit coupled to receive the rectified signal, wherein the sample output circuit samples the rectified signal under the control of the square signal and provides a peak sample signal representative of the peak value of the AC voltage.
    Type: Application
    Filed: July 9, 2014
    Publication date: January 15, 2015
    Inventors: Siran Wang, Yike Li, Kun Yi, Yuancheng Ren, Junming Zhang, En Li
  • Patent number: 8907592
    Abstract: Embodiments of LED driver circuits and the associated methods are disclosed herein. In one embodiment, the LED driver circuit comprises a switch-mode converter, a controller, a feedback circuit, and a gating circuit. The feedback circuit includes a current balance circuit. The gating circuit is responsive to both a current feedback signal and a voltage feedback signal and is configured to select one of them as the feedback signal.
    Type: Grant
    Filed: March 15, 2011
    Date of Patent: December 9, 2014
    Assignee: Monolithic Power Sytems, Inc.
    Inventors: Jin Hu, Lei Du, Yuancheng Ren, Junming Zhang, Zhijun Ye
  • Publication number: 20140285163
    Abstract: A PFC circuit includes: a switching circuit having a power switch; an on time control circuit for controlling an on time period of the power switch; a first off time control circuit; a second off time control circuit; and a logic circuit selectively controls the power switch working under CCM or DCM; when working under CCM, the first off time control circuit controls an off time period of the power switch and when working under DCM, the second off time control circuit controls the off time period of the power switch.
    Type: Application
    Filed: March 21, 2014
    Publication date: September 25, 2014
    Applicant: CHENGDU MONOLITHIC POWER SYSTEMS CO., LTD.
    Inventors: Sicon Lin, Yiqing Jin, Yuancheng Ren, Junming Zhang
  • Patent number: 8766605
    Abstract: A bridgeless PFC (power factor correction) converter with improved efficiency is disclosed. The bridgeless PFC converter comprises: a first input terminal and a second input terminal configured to receive an input AC signal; an output terminal; an inductor set comprising N inductors, wherein a first terminal of each inductor is coupled to the first input terminal; and an output stage comprising (N+1) switching circuits coupled between the output terminal and a ground node.
    Type: Grant
    Filed: December 2, 2011
    Date of Patent: July 1, 2014
    Assignee: Chengdu Monolithic Power Systems Co., Ltd.
    Inventors: Yuancheng Ren, Bo Zhang, Miao Lei, Junming Zhang, James C Moyer, Eric Yang
  • Publication number: 20140177290
    Abstract: A switch mode power supply having an output terminal configured to provide an output voltage, the switch mode power supply has a first switch and a control circuit. The control circuit is configured to provide a switching control signal to control the first switch. The control circuit is configured to provide the switching control signal based on a first pulse signal having a first frequency and a second frequency for a light load condition, and the control circuit is configured to provide the switching control signal based on a second pulse signal for a non-light load condition.
    Type: Application
    Filed: December 23, 2013
    Publication date: June 26, 2014
    Applicant: Chengdu Monolithic Power Systems Co., Ltd.
    Inventors: Junming Zhang, Hao Long, Hui Li
  • Patent number: 8749997
    Abstract: A switching mode power supply with improved peak current control is disclosed. A varying reference signal is adopted to limit the peak current in the energy storage component. The varying reference signal is an exponential function of a time period when a power switch is ON, wherein the power switch is coupled to the energy storage component. The varying reference signal may be generated by a circuit comprising a RC circuit and one or several voltage sources.
    Type: Grant
    Filed: November 3, 2011
    Date of Patent: June 10, 2014
    Assignee: Chengdu Monolithic Power Systems Co., Ltd.
    Inventors: Siran Wang, Yuancheng Ren, Junming Zhang, En Li
  • Publication number: 20140153301
    Abstract: An AC signal detector having: a rectify circuit having a first input terminal and a second input terminal configured to receive an AC signal, and an output terminal configured to provide a rectified signal based on the AC signal; a detecting circuit having an input terminal coupled to the output terminal of the rectify circuit to receive the rectified signal, and an output terminal configured to provide a square signal based on the rectified signal; and an unplug indicate circuit having an input terminal coupled to the detecting circuit to receive the square signal, and an output terminal configured to provide an unplug indicate signal based on the square signal.
    Type: Application
    Filed: June 28, 2013
    Publication date: June 5, 2014
    Inventors: Siran Wang, Yike Li, Kun Yi, Yuancheng Ren, Junming Zhang, En Li
  • Patent number: 8593841
    Abstract: A compensation circuit and method for constant current regulation of switching mode power supply are disclosed. The ringing waveform of a feedback signal, indicative of the output current of the power supply, causes error. To eliminate the error, a current source charges a capacitor in response to a demagnetizing oscillation signal indicative of the error caused by the ringing waveform of the feedback signal. The voltage across the capacitor is compared to a reference signal to generate a more accurate signal indicative of the conductive time of a secondary diode in a secondary winding of the switching mode power supply. This more accurate signal is inputted to a logic circuit to generate a constant current control signal to control a power switch of the power supply.
    Type: Grant
    Filed: November 4, 2011
    Date of Patent: November 26, 2013
    Assignee: Chengdu Monolithic Power Systems Co., Ltd.
    Inventors: Siran Wang, Yuancheng Ren, Junming Zhang, En Li
  • Publication number: 20130308349
    Abstract: A switching regulator that decreases power loss and resolves thermal issues by jumping its switching frequency to a maximum frequency when its load reaches a peak load.
    Type: Application
    Filed: May 15, 2013
    Publication date: November 21, 2013
    Applicant: MONOLITHIC POWER SYSTEMS, INC.
    Inventors: Yangwei Yu, Yuancheng Ren, Junming Zhang, Sicong Lin, Jian Zhao
  • Publication number: 20130301310
    Abstract: An isolated switching mode power supply, having: an input terminal; an output terminal; a transformer having a primary winding and a secondary winding; a primary power switch coupled to the primary winding; a secondary power switch coupled between the secondary winding and the output terminal of the power supply; a secondary controller configured to generate a frequency modulation signal based on the output voltage and the first feedback signal; a coupled device configured to provide a frequency control signal based on the output voltage and the frequency modulation signal; and a primary controller configured to provide a switching signal to control the primary power switch based on the current sense signal and the frequency control signal.
    Type: Application
    Filed: May 7, 2013
    Publication date: November 14, 2013
    Applicant: CHENGDU MONOLITHIC POWER SYSTEMS CO., LTD.
    Inventors: Siran Wang, Junming Zhang, Yuancheng Ren
  • Publication number: 20130300384
    Abstract: An isolated switching mode power supply, having: a transformer having a primary winding, a secondary winding and a third winding; a current limit comparator configured to provide a current limit signal based on the current sense signal and the peak current signal; a logic circuit configured to provide a logic control signal based on the frequency control signal and the current limit signal; a startup control circuit configured to generate a startup control signal based on the current sense signal; a load detecting circuit configured to provide a load detecting signal based on the second feedback signal and the switching signal; and a selector configured to provide the logic control signal or the startup control signal based on the load detecting signal.
    Type: Application
    Filed: May 7, 2013
    Publication date: November 14, 2013
    Applicant: CHENGDU MONOLITHIC POWER SYSTEMS CO., LTD.
    Inventors: Siran Wang, Junming Zhang, Yuancheng Ren
  • Patent number: 8581518
    Abstract: Triac dimmer compatible switching mode power supplies used as LED drivers are disclosed herein. A PFC controller is configured in the switching mode power supplies. With the PFC controller, the current keeping the triac in the on-state is supplied by the DC/DC converter, and the LC resonance is reduced.
    Type: Grant
    Filed: May 18, 2011
    Date of Patent: November 12, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Naixing Kuang, Lei Du, Junming Zhang, Yuancheng Ren
  • Patent number: 8576588
    Abstract: The present technology are directed to switching mode power supplies with primary side control. In one embodiment, the switching mode power supply provides an equivalent current signal which represents a load current. The equivalent current signal is then used to control a switching circuit in the switching mode power supply.
    Type: Grant
    Filed: January 28, 2011
    Date of Patent: November 5, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Naixing Kuang, Lei Du, Junming Zhang, Yuancheng Ren
  • Patent number: 8537584
    Abstract: Disclosed is a light load control circuit and the method accordingly where the synchronous rectification is latched off when the light load condition is detected for several successive cycles.
    Type: Grant
    Filed: June 25, 2010
    Date of Patent: September 17, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Yuancheng Ren, Junming Zhang, Lei Miao, Zhaoqi Mao
  • Patent number: 8498135
    Abstract: Embodiments of circuits and methods for a switching mode power supply are described in detail herein. In one embodiment, a switching mode power supply includes a transformer having a primary winding and a secondary winding to supply power to a load, a feedback circuit that generates a feedback signal that varies in relation to the load on the secondary winding, a switching circuit coupled to the primary winding to control current flow through the primary winding, and a control circuit coupled to the switching circuit to control the on/off status of switching circuit in response to the feedback signal and the current flow through the primary winding. The control circuit comprises a spectrum shaping circuit configured to generate a spectrum shaping signal in response to the feedback signal. The spectrum shaping signal can then be used to regulate the switching frequency and the spectrum shaping range.
    Type: Grant
    Filed: November 11, 2010
    Date of Patent: July 30, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: En Li, Junming Zhang, Yuancheng Ren
  • Patent number: 8472217
    Abstract: A switching mode power supply with a multi-mode controller is provided. The switching mode power supply may include a transformer having a primary winding and a secondary winding to supply power to a load. A feedback circuit may be included to generate a feedback signal that varies in relation to the load on the secondary winding. The multi-mode controller may include a switching circuit, a frequency control circuit and a current limiting circuit. The switching circuit may be coupled to the primary winding to control current flow through the primary winding. The frequency control circuit may control a switching frequency of the switching circuit based on the feedback signal. The current limiting circuit may limit current flow through the primary winding by causing the switching circuit to suspend current flow through the primary winding when the current reaches a peak current limit that is set based on the feedback signal.
    Type: Grant
    Filed: March 9, 2010
    Date of Patent: June 25, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: En Li, Junming Zhang, Yuancheng Ren
  • Patent number: 8400790
    Abstract: The present invention discloses a light load control circuit and the method accordingly where the synchronous rectification is latched off selectively according to the gate voltage of the synchronous rectifier.
    Type: Grant
    Filed: June 25, 2010
    Date of Patent: March 19, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Junming Zhang, Yuancheng Ren, Lei Miao, Zhaoqi Mao
  • Patent number: 8391030
    Abstract: Switching mode power supplies and associated methods of control are disclosed herein. In one embodiment, a method for controlling a switching mode power supply includes determining whether the switching mode power supply is in a burst mode. If the switching mode power supply is in the burst mode, the method includes recording a switching time with and without switching pulses to obtain a current value of an equivalent frequency and generating a peak current limit that decreases as a load becomes lighter based on the equivalent frequency, thereby maintaining the equivalent frequency at the current value above an audible range. If the switching mode power supply is not in the burst mode, the method includes continuing to monitor whether the switching mode power supply is in the burst mode.
    Type: Grant
    Filed: August 31, 2010
    Date of Patent: March 5, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: En Li, Junming Zhang
  • Patent number: 8373349
    Abstract: A circuit for controlling the switch frequency of an inverter that strikes and drives fluorescent lamps is disclosed. The circuit comprises a frequency generator and an offset circuit. The offset circuit provides a current signal in response to the lamp status. The frequency generator provides a frequency control signal in respond to the current signal so as to control the switch frequency of the inverter. When the lamp is open, the switch frequency of the inverter is higher; when the lamp is lighted, the switch frequency of the inverter is lower.
    Type: Grant
    Filed: April 21, 2010
    Date of Patent: February 12, 2013
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Junming Zhang, Jiali Cai, Lei Du, Yuancheng Ren, Eric Yang
  • Patent number: 8320139
    Abstract: A switching regulator with frequency limitation comprises a switch, a current sensing circuit, a voltage feedback circuit, a control circuit and a frequency limitation circuit. The current sensing circuit senses the current flowing through the switch and generating a current sensing signal representative of it. The voltage feedback circuit senses the output signal of the switching regulator and generates a feedback signal accordingly. The control circuit compares the current sensing signal with the feedback signal and turns off the switch based on the comparison result. The frequency limitation circuit is electrically coupled to the control circuit to limit the switching frequency of the switch.
    Type: Grant
    Filed: April 16, 2010
    Date of Patent: November 27, 2012
    Assignee: Monolithic Power Systems, Inc.
    Inventors: Jin Hu, James C. Moyer, Junming Zhang, Yuancheng Ren