Patents by Inventor Hang-Seok Choi

Hang-Seok Choi 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: 7684215
    Abstract: The present invention relates to a Switching Mode Power Supply (SMPS) and a driving method thereof. To this end, the present invention provides a SMPS, which is driven in either a Continuous Conduction Mode (CCM) or Discontinuous Conduction Mode (DCM) in accordance with a determination of a time when a voltage between a first stage and a second stage of the switching transistor is resonated. In accordance with the present invention, the SMPS of a quasi-resonant switching mode can be driven with high efficiency regardless of a signal level of an input voltage and the amount of an output terminal load.
    Type: Grant
    Filed: July 26, 2007
    Date of Patent: March 23, 2010
    Assignee: Fairchild Korea Semiconductor, Ltd.
    Inventors: Young-Bae Park, Hang-Seok Choi
  • Publication number: 20100039834
    Abstract: In a power converter, a primary coil of a transformer receives an input voltage, and a first terminal of a switch is coupled to the primary coil. An output unit includes a secondary coil of the transformer, and outputs an output voltage to which the input voltage is converted by the transformer. A switching controller receives a feedback voltage corresponding to the output voltage and a sensing voltage corresponding to a current flowing between the first terminal and a second terminal of the switch. The switching controller determines whether to perform an operation of a burst mode based on the feedback voltage. The switching controller generates a control signal by comparing the sensing voltage with a comparison voltage during a first period of the burst mode, generates the control signal by comparing the sensing voltage with a voltage corresponding to the feedback voltage during a second period of the burst mode, and transmits the control signal to a control terminal of the switch.
    Type: Application
    Filed: August 3, 2009
    Publication date: February 18, 2010
    Inventors: Sang-Cheol MOON, Hang-Seok CHOI, Young-Bae PARK
  • Publication number: 20100014331
    Abstract: A power converter according to the present invention includes a power supply unit, an output unit, and a switching controller. The power supply unit includes a primary coil of a transformer that receives an input voltage, a gate electrode, and a switch having a first electrode and a second electrode that is connected to the primary coil. The output unit includes a secondary coil of the transformer, and outputs an output voltage that is converted from the input voltage by the transformer. The switching controller includes a feedback terminal that receives a feedback voltage corresponding to the output voltage, generates a burst voltage by compensating the feedback voltage according to a maximum current value that can flow between the second electrode and the first electrode of the switch, determines whether to perform a burst mode operation according to the burst voltage, and transmits a gate signal according to performance of the burst mode operation to the gate electrode of the switch.
    Type: Application
    Filed: May 26, 2009
    Publication date: January 21, 2010
    Inventors: Sang-Cheol MOON, Hang-Seok CHOI, Young-Bae PARK
  • Publication number: 20100002474
    Abstract: The present invention relates to a switch controller and a converter having the same. The converter according to the present invention includes a power transfer device that transmits input power to an output terminal as output power, a power switch connected to a first end of the power transfer device and that controls power transmission of the power transfer device, and a switch controller that controls switching operation of the power switch. The switch controller receives an output voltage detection signal corresponding to an output voltage according to the power transmitted from the power transfer device, generates a duty control signal corresponding to a difference between the output voltage detection signal and a reference signal for controlling the output voltage, and determines turn-on/off of the power switch by using the duty control signal, and a DC gain of a feedback transfer function between the reference signal and the output voltage has a constant value.
    Type: Application
    Filed: July 2, 2009
    Publication date: January 7, 2010
    Inventors: Sang-Cheol Moon, Hang-Seok Choi, Young-Bae Park
  • Publication number: 20090323374
    Abstract: The present invention relates to a switch control device and a converter including the same. According to an exemplary embodiment of the present invention, the switch control device includes a PWM controller for forcing a power switch to turn on when the power switch is turned off during a predetermined period, a current sensor for determining whether a current flows through the power switch, and a conditional counter for determining that an input voltage is input to a power transmission element by using a sense result of the current sensor and a number of times that the PWM controller turns on the power switch by force.
    Type: Application
    Filed: June 17, 2009
    Publication date: December 31, 2009
    Applicant: Fairchild Korea Semiconductor Ltd.
    Inventors: Young-Bae Park, Hang-Seok Choi, Ki-Tae Kim
  • Publication number: 20090251926
    Abstract: A converter is disclosed for using at least one switch to convert an input signal to a square wave signal, and using the square wave signal to generate an output voltage. The converter converts the square wave signal by a switching operation of a switch and generates the output voltage, and includes a switch controller for controlling the switching operation. The switch controller generates a first signal VCT having a first period that varies according to an output voltage, controls the switching operation of the switch by using the first signal, detects the output voltage, a first current Ids2 flowing through the switch, and a level of the first signal, and controls a burst mode according to the detection results.
    Type: Application
    Filed: July 25, 2008
    Publication date: October 8, 2009
    Inventors: Hang-Seok Choi, Young-Bae Park, Jae-Hwoan Chi, Gwan-Bon Koo
  • Publication number: 20090251929
    Abstract: A converter and a driving method thereof are provided. The converter includes first and second switches, and generates a square wave signal according to operations of the first and second switches. The converter includes a first capacitor and a primary coil, and resonates a driving voltage by using a driving voltage with the first capacitor and the primary coil so as to generate a driving current. The converter includes a secondary coil that forms the primary coil and the transformer, and generates output power by rectifying a current and a voltage generated in the secondary coil. In addition, the converter detects the phase of the driving current, and increases switching frequencies of the first and second switches if a phase difference of the phase of the driving current and that of the driving voltage is smaller than a predetermined value.
    Type: Application
    Filed: April 2, 2009
    Publication date: October 8, 2009
    Applicant: Fairchild Korea Semiconductor Ltd.
    Inventor: Hang-Seok Choi
  • Publication number: 20090206805
    Abstract: The present invention relates to a converter and a driving method thereof. The converter includes a switch controller that controls switching operation of a master switch and a slave switch. The switch controller detects a center point of one switching operation period of the master switch by using an internal triangular wave having a period that is the same as that of the one switching operation period, and starts the switching operation of the slave switch at the detected point. The internal triangular wave signal has a waveform that varies within one period, and detects a crossing point of an average value of the internal triangular wave and the internal triangular wave as a center point of one switching operation period of the master switch.
    Type: Application
    Filed: December 24, 2008
    Publication date: August 20, 2009
    Inventors: Hang-Seok Choi, Gwan-Bon Koo, Young-Bae Park
  • Publication number: 20090206809
    Abstract: In an interleaved switching converter, a first converter including a first switch is coupled to a second converter including a second switch. A switching controller for controlling the first switch and the second switch outputs a second control signal for operating the second switch based a first control signal for operating the first switch. A phase shift between the first control signal and the second control signal is 180 degrees.
    Type: Application
    Filed: October 24, 2008
    Publication date: August 20, 2009
    Inventors: Gwan-Bon Koo, Young-Bae Park, Hang-Seok Choi
  • Publication number: 20090196074
    Abstract: A resonant converter includes a square wave generator including a first switch and a second switch, and generating a first square wave corresponding to an input voltage by alternately turning on/off the first and second switches; a resonator including a first coil of a primary coil of a transformer, and generating a resonance waveform corresponding to the first square wave; and an output unit including a second coil of a secondary coil of the transformer, and outputting a voltage corresponding to a current generated in the second coil corresponding to the resonance waveform.
    Type: Application
    Filed: January 28, 2009
    Publication date: August 6, 2009
    Inventor: Hang-Seok Choi
  • Publication number: 20090175056
    Abstract: This invention relates to a synchronous rectifier for LLC resonant converter. This method allows simple drive method for the synchronous rectifier MOSFETS by using the transformer secondary winding voltage and one-shot vibrator. The synchronous rectifier MOSFETs are turned on by being triggered to the transformer secondary side winding voltage and turned off after predetermined time set by one shot vibrator. The predetermined time is set by the resonant period of the resonant network.
    Type: Application
    Filed: December 24, 2008
    Publication date: July 9, 2009
    Inventor: Hang-Seok Choi
  • Patent number: 7525819
    Abstract: A switching mode power supply and method for generating a bias voltage is described. The bias voltage is generated by using a current source coupled to a primary coil of a transformer during the start-up of the switching mode power supply. The generation of the bias voltage through the current source is stopped at a second time, a delay time after a first time when the bias voltage becomes essentially equal to a reference voltage that is an operational voltage of a PWM controller. The switching operation of a main switch is started after the first time, when the bias voltage exceeded the operational voltage. In this interval the bias voltage is also generated by the secondary coil of the transformer.
    Type: Grant
    Filed: February 28, 2006
    Date of Patent: April 28, 2009
    Assignee: Fairchild Korea Semiconductor, Ltd.
    Inventor: Hang-Seok Choi
  • Publication number: 20090091955
    Abstract: A switching mode power supply (SMPS) and a driving method thereof are provided. The SMPS includes a power supply block that includes a first switch coupled to a first coil of a primary side of a transformer for converting an input voltage, wherein the power supply block supplies power to a second coil and a third coil of a secondary side of the transformer according to operation of the first switch; and a PWM signal generator determines a turn-on time of the first switch according to the input voltage, and the turn-on time is determined regardless of a power magnitude of an output terminal connected to the second coil. Accordingly, screen noise due to a ripple can be eliminated and stress on the switch breakdown due to excessive power input can be reduced to enable an SMPS with stable driving.
    Type: Application
    Filed: March 28, 2008
    Publication date: April 9, 2009
    Inventors: Hang-Seok Choi, Jin-Tae Kim, Jae-Hwoan Chi
  • Publication number: 20080290850
    Abstract: A switch control device, a switch control method, and a converter using the same are disclosed. The converter includes: a switch; an energy transfer element that converts input energy into output energy according to a switching operation of the switch; and a switch control device that generates a first signal, which is maintained at a first level during a first interval starting from a first time at which the switch is turned on by using a feedback signal corresponding to the output energy and is then gradually lowered from the first level to the feedback signal during a second interval, and controls the switching operation of the switch by using a second signal corresponding to a current flowing at the switch and the first signal. A malfunction due to an LEC can be effectively prevented, and the converter and the converter controller can be implemented to be compact and low-priced.
    Type: Application
    Filed: May 21, 2008
    Publication date: November 27, 2008
    Applicant: Sidley Austin LLP
    Inventors: Jin-Tae Kim, Gwan-Bon Koo, Hang Seok Choi
  • Publication number: 20080278131
    Abstract: A switching mode power supply includes: a power supply unit that comprises a switch that is coupled to a primary coil at a primary side of a transformer for converting an input DC voltage, and that supplies power to a secondary coil and a tertiary coil at a secondary side of the transformer according to an operation of the switch; a switching controller that receives a feedback voltage corresponding to a first voltage generated in the secondary coil at the secondary side of the transformer, and receives a detection signal corresponding to a current flowing to the switch to control an on/off operation of the switch; and a feedback signal generator that receives the first voltage and the switching control signal, samples the first voltage by using first pulse strings, and generates the feedback voltage according to a level of the first voltage sampled by a first pulse in the first pulse strings, wherein a toggling time of the first pulse strings is changed in a first period for sampling the first voltage, and a
    Type: Application
    Filed: May 9, 2008
    Publication date: November 13, 2008
    Inventors: Young-Bae Park, Gwan-Bon Koo, Hang-Seok Choi
  • Publication number: 20080266907
    Abstract: Disclosed are a switch controller, a switch control method, a converter using the same, and a driving method thereof. A first voltage is generated by using a voltage that is input to an input terminal, and a soft start signal is generated by using the first voltage during a soft start duration. A switching operation is controlled by using the soft start signal during the soft start duration.
    Type: Application
    Filed: April 25, 2008
    Publication date: October 30, 2008
    Inventors: Jin-Tae Kim, Gwan-Bon Koo, Hang Seok Choi
  • Publication number: 20080259659
    Abstract: A converter and a driving method thereof are provided. The converter can determine the output short state of the converter after the soft start is finished by using a detection signal that corresponds to an input signal while a switched is turned on and that corresponds to an output signal while the switch is turned off, so as to convert the input signal into the output signal according to a switching operation of the switch. The converter can determine the overload state of the converter by using a feedback voltage corresponding to the output signal, and terminate the switching operation when the converter is in an output short state or overload state.
    Type: Application
    Filed: March 25, 2008
    Publication date: October 23, 2008
    Inventors: Hang-Seok Choi, Young-Bae Park, Gwan-Bon Koo, Jin-Tae Kim
  • Publication number: 20080130328
    Abstract: A converter control circuit applicable to various topologies of converters each employing two switching devices is disclosed. The converter control circuit includes an oscillator for generating a pulse signal and triangle-wave signal of a certain frequency, a switching control signal output unit for outputting a switching control signal to control ON/OFF of a plurality of switching devices based on a duty ratio determined from a feedback signal which is applied to a feedback terminal, a mode select signal generator for generating a mode select signal for determination of a control mode of a converter in response to the feedback signal applied to the feedback terminal, and a mode selecting unit for selecting the control mode in response to the mode select signal.
    Type: Application
    Filed: July 31, 2007
    Publication date: June 5, 2008
    Inventor: Hang Seok Choi
  • Publication number: 20080130324
    Abstract: The present invention relates to a switch mode power supply and a driving method for reducing switching loss and audible noise in the burst mode. The switch mode power supply includes a main switch, a power supply, an output unit, and a switch controller. The power supply includes a transformer having a primary coil connected to the main switch, and supplies power to a secondary coil of the transformer according to the operation of the main switch. The output unit is connected to the secondary coil of the transformer and outputs power supplied to the secondary coil of the transformer.
    Type: Application
    Filed: August 1, 2007
    Publication date: June 5, 2008
    Inventors: Hang-Seok Choi, Jae-Hwoan Chi
  • Publication number: 20080123380
    Abstract: The present invention relates to a Switching Mode Power Supply (SMPS) and a driving method thereof. To this end, the present invention provides a SMPS, which is driven in either a Continuous Conduction Mode (CCM) or Discontinuous Conduction Mode (DCM) in accordance with a determination of a time when a voltage between a first stage and a second stage of the switching transistor is resonated. In accordance with the present invention, the SMPS of a quasi-resonant switching mode can be driven with high efficiency regardless of a signal level of an input voltage and the amount of an output terminal load.
    Type: Application
    Filed: July 26, 2007
    Publication date: May 29, 2008
    Inventors: Young-Bae Park, Hang-Seok Choi