Patents by Inventor Stefan Maireanu

Stefan Maireanu 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: 10797535
    Abstract: In accordance with some embodiments of the present invention, a method of determining a Q-factor in a transmit circuit with a resonant circuit includes setting a system voltage; performing a coarse scan to determine a course resonant frequency; performing a fine scan based on the course scan to determine a resonant frequency; performing a final measurement at the resonant frequency to determine an average system voltage and an average peak voltage of the resonant circuit; calculating a Q parameter from the average system voltage and the average peak voltage; and calculating the Q-factor from the Q parameter.
    Type: Grant
    Filed: October 8, 2018
    Date of Patent: October 6, 2020
    Assignee: Integrated Device Technology, Inc.
    Inventors: Nicholaus Smith, Stefan Maireanu, Haiwen Jiang, David Wilson
  • Publication number: 20190109499
    Abstract: In accordance with some embodiments of the present invention, a method of determining a Q-factor in a transmit circuit with a resonant circuit includes setting a system voltage; performing a coarse scan to determine a course resonant frequency; performing a fine scan based on the course scan to determine a resonant frequency; performing a final measurement at the resonant frequency to determine an average system voltage and an average peak voltage of the resonant circuit; calculating a Q parameter from the average system voltage and the average peak voltage; and calculating the Q-factor from the Q parameter.
    Type: Application
    Filed: October 8, 2018
    Publication date: April 11, 2019
    Inventors: Nicholaus Smith, Stefan Maireanu, Haiwen Jiang, David Wilson
  • Patent number: 9130378
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Grant
    Filed: November 27, 2013
    Date of Patent: September 8, 2015
    Assignee: O2Micro, Inc.
    Inventors: William Densham, Constantin Bucur, Flavius Lupu, Jiun Heng Goh, Stefan Maireanu
  • Patent number: 8907625
    Abstract: A battery management chip may include a battery management unit and a vertical bus circuit. The battery management unit can monitor a cell status of multiple cells in a battery module coupled to the battery management chip in response to an instruction from a host processor. The vertical bus circuit may transfer the instruction from the host processor to the battery management unit. The vertical bus circuit may include a first receiver, a command processor and a first transmitter. The first receiver can receive a first pair of differential input data signals. The command processor can process the first pair of differential input data signals. The first transmitter can output a first pair of differential output data signals.
    Type: Grant
    Filed: July 15, 2011
    Date of Patent: December 9, 2014
    Assignee: O2Micro, Inc.
    Inventors: Allan Flippin, William Densham, Jiun Heng Goh, Constantin Bucur, Flavius Lupu, Stefan Maireanu
  • Publication number: 20140084871
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Application
    Filed: November 27, 2013
    Publication date: March 27, 2014
    Applicant: O2Micro Inc.
    Inventors: William DENSHAM, Constantin BUCUR, Flavius LUPU, Jiun Heng GOH, Stefan MAIREANU
  • Patent number: 8598844
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Grant
    Filed: October 21, 2011
    Date of Patent: December 3, 2013
    Assignee: O2Micro, Inc.
    Inventors: William Densham, Constantin Bucur, Flavius Lupu, Jiun Heng Goh, Stefan Maireanu
  • Publication number: 20130019037
    Abstract: A battery management chip may include a battery management unit and a vertical bus circuit. The battery management unit can monitor a cell status of multiple cells in a battery module coupled to the battery management chip in response to an instruction from a host processor. The vertical bus circuit may transfer the instruction from the host processor to the battery management unit. The vertical bus circuit may include a first receiver, a command processor and a first transmitter. The first receiver can receive a first pair of differential input data signals. The command processor can process the first pair of differential input data signals. The first transmitter can output a first pair of differential output data signals.
    Type: Application
    Filed: July 15, 2011
    Publication date: January 17, 2013
    Inventors: Allan Flippin, William Densham, Jiun Heng Goh, Constantin Bucur, Flavius Lupu, Stefan Maireanu
  • Patent number: 8294421
    Abstract: A cell balancing circuit for balancing battery cells includes a transformer and a switching controller. The transformer has a primary winding and a secondary winding. The switching controller can select a first cell coupled to the primary winding and select a second cell coupled to the secondary winding. The first cell and the second cell are coupled in series. The first cell has a cell voltage that is greater than the second cell. The cell balancing circuit further includes a controller coupled to the primary winding. The controller controls energy from the first cell to the primary winding so as to transfer the energy from the first cell to the second cell to balance the battery cells.
    Type: Grant
    Filed: September 2, 2009
    Date of Patent: October 23, 2012
    Assignee: O2Micro Inc
    Inventors: Constantin Bucur, Stefan Maireanu
  • Publication number: 20120081126
    Abstract: A battery monitoring system for a battery including multiple battery cells is disclosed. The battery monitoring system includes multiple first switch sets coupled across the battery cells respectively, an energy storage element, and a comparator coupled to the energy storage element via a second switch set. The energy storage element samples cell voltages of the battery cells via the first switch sets respectively. The comparator compares a respective cell voltage with a first reference signal to determine whether a fault condition occurs on a respective battery cell. The second switch set and one of the first switch sets are turned on alternately.
    Type: Application
    Filed: September 30, 2010
    Publication date: April 5, 2012
    Inventors: Stefan MAIREANU, William DENSHAM, Jiun Heng GOH, Flavius LUPU, Constantin BUCUR
  • Patent number: 8148942
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Grant
    Filed: November 5, 2009
    Date of Patent: April 3, 2012
    Assignee: O2Micro International Limited
    Inventors: William Densham, Constantin Bucur, Flavius Lupu, Jiun Heng Goh, Stefan Maireanu
  • Publication number: 20120038323
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Application
    Filed: October 21, 2011
    Publication date: February 16, 2012
    Inventors: William DENSHAM, Constantin BUCUR, Flavius LUPU, Jiun Heng GOH, Stefan MAIREANU
  • Patent number: 7977911
    Abstract: A power supply system can include a primary power supply coupled to an output, and a secondary power supply coupled to the output. The primary power supply provides power to the output when a voltage level of the secondary power supply is less than a first predetermined level. The secondary power supply provides power to the output when the voltage level of the secondary power supply is greater than the first predetermined level. The secondary power supply not only provides power to the output, but also charges the primary power supply when the voltage level of the secondary power supply is greater than a second predetermined level that is greater than the first predetermined level.
    Type: Grant
    Filed: October 1, 2007
    Date of Patent: July 12, 2011
    Assignee: O2 Micro, Inc.
    Inventors: Stefan Maireanu, Alex Hartular, Chun Lu, Jianping Xu, Xinhe Su, Xiaodong Wang
  • Publication number: 20110101916
    Abstract: In a power converter, a primary winding receives an input power. In addition, multiple secondary windings transform the input power into multiple charging currents to charge a set of cells via a set of paths. The multiple secondary windings further balance the set of cells based on the charging currents. A ratio between a first turn number of a first secondary winding of the secondary windings and a second turn number of a second secondary winding of the secondary windings is determined by a nominal voltage ratio between two corresponding cells of the set of cells.
    Type: Application
    Filed: November 5, 2009
    Publication date: May 5, 2011
    Inventors: William DENSHAM, Constantin BUCUR, Flavius LUPU, Jiun Heng GOH, Stefan MAIREANU
  • Patent number: 7804278
    Abstract: In one embodiment, a battery management system includes a charger controller for controlling a charging current of a battery according to a status of a load which is powered by the battery, and a counter coupled to the charger controller for determining a charging time according to such status. Advantageously, a first charging current is selected when the load is off. A second charging current that is less than the first charging current is selected when the load is on. Furthermore, a frequency of the counter is set to a first frequency when the load is off. The frequency is set to a second frequency that is less than the first frequency when the load is on.
    Type: Grant
    Filed: July 25, 2007
    Date of Patent: September 28, 2010
    Assignee: O2Micro International Ltd.
    Inventors: Stefan Maireanu, Chun Lu, Jianping Xu, Xiaohua Lei, Zhitong Lei, Yongqiang Yu
  • Publication number: 20100225275
    Abstract: A cell balancing circuit for balancing battery cells includes a transformer and a switching controller. The transformer has a primary winding and a secondary winding. The switching controller can select a first cell coupled to the primary winding and select a second cell coupled to the secondary winding. The first cell and the second cell are coupled in series. The first cell has a cell voltage that is greater than the second cell. The cell balancing circuit further includes a controller coupled to the primary winding. The controller controls energy from the first cell to the primary winding so as to transfer the energy from the first cell to the second cell to balance the battery cells.
    Type: Application
    Filed: September 2, 2009
    Publication date: September 9, 2010
    Inventors: Constantin Bucur, Stefan Maireanu
  • Patent number: 7737662
    Abstract: A power system for managing charging, discharging and protection of rechargeable batteries is disclosed. The power system mainly includes a power system. The power system includes a switching circuit coupled to the rechargeable batteries to charge and discharge the rechargeable batteries. The power system includes a power management unit to control the switching circuit. The power system includes a temperature sensing circuit to monitor a temperature of the batteries, voltage detectors to monitor voltages of the batteries, and current detectors to monitor a current of the batteries. If an abnormal condition is sensed by the power management unit when the power system is in an operating mode, the power management unit will terminate the operating mode by switching off the switching circuit to protect the batteries and the power system.
    Type: Grant
    Filed: December 26, 2006
    Date of Patent: June 15, 2010
    Assignee: O2Micro International Ltd.
    Inventors: Chun Lu, Stefan Maireanu, Luyang Luo, Lin Tang, Mingzhi He, Jianping Xu
  • Patent number: 7531989
    Abstract: The present invention is a battery fuel gauge circuit for measuring the capacity of a battery pack. The battery fuel gauge circuit includes an amplifier circuit, a correction circuit, a plurality of comparators, and a multiplexer. The amplifier circuit can sense a discharge current flowing through a sense resistor and a variable temperature from the battery pack and generate a first and a second voltage signals, which are corrected by the correction circuit and compared with a reference voltage by the plurality of comparators. After correction and comparison, the multiplexer can transmit the compared signals to an external indicating circuit that controls the display of the capacity of the battery pack.
    Type: Grant
    Filed: May 9, 2006
    Date of Patent: May 12, 2009
    Assignee: 02Micro International Ltd.
    Inventor: Stefan Maireanu
  • Publication number: 20080197812
    Abstract: In one embodiment, a battery management system includes a charger controller for controlling a charging current of a battery according to a status of a load which is powered by the battery, and a counter coupled to the charger controller for determining a charging time according to such status. Advantageously, a first charging current is selected when the load is off. A second charging current that is less than the first charging current is selected when the load is on. Furthermore, a frequency of the counter is set to a first frequency when the load is off. The frequency is set to a second frequency that is less than the first frequency when the load is on.
    Type: Application
    Filed: July 25, 2007
    Publication date: August 21, 2008
    Inventors: Stefan Maireanu, Chun Lu, Jianping Xu, Xiaohua Lei, Zhitong Lei, Yongqiang Yu
  • Publication number: 20080191557
    Abstract: A power supply system can include a primary power supply coupled to an output, and a secondary power supply coupled to the output. The primary power supply provides power to the output when a voltage level of the secondary power supply is less than a first predetermined level. The secondary power supply provides power to the output when the voltage level of the secondary power supply is greater than the first predetermined level. The secondary power supply not only provides power to the output, but also charges the primary power supply when the voltage level of the secondary power supply is greater than a second predetermined level that is greater than the first predetermined level.
    Type: Application
    Filed: October 1, 2007
    Publication date: August 14, 2008
    Applicant: O2Micro Inc.
    Inventors: Stefan Maireanu, Alex Hartular, Chun Lu, Jianping Xu, Xinhe Su, Xiaodong Wang
  • Publication number: 20080150488
    Abstract: A power system for managing charging, discharging and protection of rechargeable batteries is disclosed. The power system mainly includes a power system. The power system includes a switching circuit coupled to the rechargeable batteries to charge and discharge the rechargeable batteries. The power system includes a power management unit to control the switching circuit. The power system includes a temperature sensing circuit to monitor a temperature of the batteries, voltage detectors to monitor voltages of the batteries, and current detectors to monitor a current of the batteries. If an abnormal condition is sensed by the power management unit when the power system is in an operating mode, the power management unit will terminate the operating mode by switching off the switching circuit to protect the batteries and the power system.
    Type: Application
    Filed: December 26, 2006
    Publication date: June 26, 2008
    Inventors: Chun Lu, Stefan Maireanu, Luyang Luo, Lin Tang, Mingzhi He, Jianping Xu