Patents by Inventor Richard W. Farrington

Richard W. Farrington 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: 20130058133
    Abstract: A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.
    Type: Application
    Filed: March 30, 2012
    Publication date: March 7, 2013
    Applicant: SynQor, Inc.
    Inventors: Richard W. Farrington, Martin F. Schlecht
  • Patent number: 8149597
    Abstract: A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.
    Type: Grant
    Filed: August 27, 2010
    Date of Patent: April 3, 2012
    Assignee: SynQor, Inc.
    Inventors: Richard W. Farrington, Martin F. Schlecht
  • Publication number: 20110187191
    Abstract: A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.
    Type: Application
    Filed: August 27, 2010
    Publication date: August 4, 2011
    Inventors: Richard W. Farrington, Martin F. Schlecht
  • Publication number: 20110176333
    Abstract: In a power converter, the duty cycle of a primary winding circuit causes near continuous flow of power through the primary and secondary winding circuits during normal operation. By providing no regulation during normal operation, a very efficient circuit is obtained with a synchronous rectifier in the secondary operating at all times. However, during certain conditions such as start up or a short-circuit, the duty cycle of the primary may be reduced to cause freewheeling periods. A normally non-regulating isolation stage may be followed by plural non-isolating regulation stages. To simplify the gate drive, the synchronous rectifiers may be allowed to turn off for a portion of the cycle when the duty cycle is reduced. A filter inductance of the secondary winding circuit is sufficient to minimize ripple during normal operation, but allows large ripple when the duty cycle is reduced. By accepting large ripple during other than normal operation, a smaller filter inductance can be used.
    Type: Application
    Filed: October 19, 2010
    Publication date: July 21, 2011
    Applicant: SynQor, Inc.
    Inventors: Martin F. Schlecht, Richard W. Farrington
  • Patent number: 7787261
    Abstract: A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.
    Type: Grant
    Filed: November 1, 2007
    Date of Patent: August 31, 2010
    Assignee: SynQor, Inc.
    Inventors: Richard W. Farrington, Martin F. Schlecht
  • Publication number: 20080211304
    Abstract: A dc-dc converter system comprises a quasi-regulated bus converter and plural regulation stages that regulate the output of the bus converter. The bus converter has at least one controlled rectifier with a parallel uncontrolled rectifier. A control circuit controls the controlled rectifier to cause a normally non-regulated mode of operation through a portion of an operating range of source voltage and a regulated output during another portion. The bus converter may be an isolation stage having primary and secondary transformer winding circuits. For the non-regulated output, each primary winding has a voltage waveform with a fixed duty cycle. The fixed duty cycle causes substantially uninterrupted flow of power during non-regulated operation. Inductors at the bus converter input and in a filter at the output of the bus converter may saturate during non-regulated operation.
    Type: Application
    Filed: November 1, 2007
    Publication date: September 4, 2008
    Applicant: SynQor, Inc.
    Inventors: Richard W. Farrington, Martin F. Schlecht
  • Publication number: 20080175024
    Abstract: In a power converter, the duty cycle of a primary winding circuit causes near continuous flow of power through the primary and secondary winding circuits during normal operation. By providing no regulation during normal operation, a very efficient circuit is obtained with a synchronous rectifier in the secondary operating at all times. However, during certain conditions such as start up or a short-circuit, the duty cycle of the primary may be reduced to cause freewheeling periods. A normally non-regulating isolation stage may be followed by plural non-isolating regulation stages. To simplify the gate drive, the synchronous rectifiers may be allowed to turn off for a portion of the cycle when the duty cycle is reduced. A filter inductance of the secondary winding circuit is sufficient to minimize ripple during normal operation, but allows large ripple when the duty cycle is reduced. By accepting large ripple during other than normal operation, a smaller filter inductance can be used.
    Type: Application
    Filed: September 14, 2007
    Publication date: July 24, 2008
    Inventors: Martin F. Schlecht, Richard W. Farrington
  • Patent number: 7272021
    Abstract: In a power converter, the duty cycle of a primary winding circuit causes near continuous flow of power through the primary and secondary winding circuits during normal operation. By providing no regulation during normal operation, a very efficient circuit is obtained with a synchronous rectifier in the secondary operating at all times. However, during certain conditions such as start up or a short-circuit, the duty cycle of the primary may be reduced to cause freewheeling periods. A normally non-regulating isolation stage may be followed by plural non-isolating regulation stages. To simplify the gate drive, the synchronous rectifiers may be allowed to turn off for a portion of the cycle when the duty cycle is reduced. A filter inductance of the secondary winding circuit is sufficient to minimize ripple during normal operation, but allows large ripple when the duty cycle is reduced. By accepting large ripple during other than normal operation, a smaller filter inductance can be used.
    Type: Grant
    Filed: April 20, 2006
    Date of Patent: September 18, 2007
    Assignee: SynQor, Inc.
    Inventors: Martin F. Schlecht, Richard W. Farrington
  • Patent number: 6459600
    Abstract: The present invention provides a method for preventing a fault condition in a DC-DC converter (10, 20, 50) having a first secondary winding (Ns1) coupled to a first synchronous rectifier (SQ1) and a second secondary winding (Ns2) coupled to a second synchronous rectifier (SQ2). The first synchronous rectifier (SQ1) is turned on based on a voltage across the first secondary winding (Ns1) and is turned off based on a first driver signal. The second synchronous rectifier (SQ2) is turned on based on a voltage across the second secondary winding (Ns2) and is turned off based on a second driver signal. The present invention also provides a DC-DC converter (10, 20, 50) wherein a first control circuit is coupled to and controls the first synchronous rectifier (SQ1) pursuant to the method described above, and a second control circuit is coupled to and controls the second synchronous rectifier (SQ2) pursuant to the method described above.
    Type: Grant
    Filed: January 27, 2001
    Date of Patent: October 1, 2002
    Assignee: Ericsson, Inc.
    Inventors: Richard W. Farrington, Claes Svardsjo, William Hart
  • Publication number: 20010033506
    Abstract: The present invention provides a method for preventing a fault condition in a DC-DC converter (10, 20, 50) having a first secondary winding (Ns1) coupled to a first synchronous rectifier (SQ1) and a second secondary winding (Ns2) coupled to a second synchronous rectifier (SQ2). The first synchronous rectifier (SQ1) is turned on based on a voltage across the first secondary winding (Ns1) and is turned off based on a first driver signal. The second synchronous rectifier (SQ2) is turned on based on a voltage across the second secondary winding (Ns2) and is turned off based on a second driver signal. The present invention also provides a DC-DC converter (10, 20, 50) wherein a first control circuit is coupled to and controls the first synchronous rectifier (SQ1) pursuant to the method described above, and a second control circuit is coupled to and controls the second synchronous rectifier (SQ2) pursuant to the method described above.
    Type: Application
    Filed: January 27, 2001
    Publication date: October 25, 2001
    Inventors: Richard W. Farrington, Claes Svardsjo, William Hart
  • Patent number: 6256214
    Abstract: A self-driven synchronous rectifier circuit having synchronous rectifiers with floating gates for a power converter or signal transformer. The circuit comprises a transformer (49, 70) having a secondary winding with a first and second terminal, a first synchronous rectifier (SQ1) coupled to the first transformer secondary winding first terminal and having a control terminal floating relative to ground and a first drive circuit coupled to the first synchronous rectifier floating control terminal and controlling the first synchronous rectifier. A first control signal is coupled to the first drive circuit, where the first control signal controls the first drive circuit as a function of a polarity reversal of a voltage across the first transformer (49, 70). A second synchronous rectifier (SQ2) is coupled to the first transformer secondary winding second terminal and has a control terminal floating relative to ground.
    Type: Grant
    Filed: March 11, 1999
    Date of Patent: July 3, 2001
    Assignee: Ericsson Inc.
    Inventors: Richard W. Farrington, William Hart
  • Patent number: 6188592
    Abstract: A self-driven synchronous rectifier circuit (50) for a DC—DC power converter. The circuit comprises a primary transformer (16), a first synchronous rectifier (SQ1) coupled to the primary transformer (16), a second synchronous rectifier (SQ2) coupled to the primary transformer (16), an external drive circuit (18). The circuit (50) also comprises a plurality of switches (SQ3, SQ4) controllably coupled to second synchronous rectifier (SQ2). The external drive circuit (18) provides turn-off signaling for both synchronous rectifiers (SQ1, SQ2) Turn-on signaling provided for first synchronous rectifier (SQ1) by the primary transformer (16) turn-on signaling for second synchronous rectifier (SQ2) is provided by the external drive circuit (18).
    Type: Grant
    Filed: November 5, 1999
    Date of Patent: February 13, 2001
    Assignee: Ericsson Inc.
    Inventors: Richard W. Farrington, Claes Svardsjo, William Hart
  • Patent number: 6166927
    Abstract: A push-pull converter for converting an input voltage to a selectable output voltage is disclosed. The push-pull converter includes a pair of primary switches and a pair of primary windings of a transformer. The voltage stress across the primary switches is regulated by means of a clamp capacitor. The clamp capacitor clamps the voltage of the primary switches during the reset of the primary windings of the transformer. An alternate embodiment is also disclosed in which the voltage stress across the primary switches is regulated by means of two clamp capacitors. The clamp capacitor clamps the voltage of the primary switches during the reset of the primary windings of the transformer. The clamp capacitors extend the transformer reset period to include the lagging dead time for the corresponding switches, as well as the complementary powering stage. Current in the output section during the dead times is permitted by means of an additional diode, therein.
    Type: Grant
    Filed: July 23, 1999
    Date of Patent: December 26, 2000
    Assignee: Ericsson Inc.
    Inventors: Richard W. Farrington, William Hart
  • Patent number: 6060867
    Abstract: In a power converter having a power switch, a rectifier and a snubber circuit having an auxiliary switch that moderates reverse recovery currents associated with the rectifier, a driver for the auxiliary switch, a method of driving the auxiliary switch and a power converter employing the driver and method. In one embodiment, the driver includes a first driver switch, coupled between the power switch and the auxiliary switch, that allows the auxiliary switch to turn on concurrently with the power switch. The driver also includes a second driver switch, coupled between the auxiliary switch and an output of the power converter, that prevents a voltage of the auxiliary switch from rising above an output voltage of the power converter to assist the auxiliary switch in turning off.
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: May 9, 2000
    Assignee: Lucent Technologies Inc.
    Inventors: Richard W. Farrington, William P. Gardiner
  • Patent number: 6038148
    Abstract: A self-driven synchronous rectifier circuit (42) for a power converter. The circuit comprises a transformer (49, 70) having a secondary winding with a first and second terminal, a first synchronous rectifier (14) coupled to the second transformer terminal and having a control terminal, and a second synchronous rectifier (16) coupled to the first transformer terminal and having a control terminal. The circuit (42) also comprises a first switch (44) coupled to the first synchronous rectifier (14) control terminal, and a second switch (46) coupled to the second synchronous rectifier (16) control terminal. The first (44) and second switch (46) are also coupled to the secondary winding. Switching transitions of the first (14) and second (16) synchronous rectifiers are initiated by a polarity reversal of the voltage of the secondary transformer winding.
    Type: Grant
    Filed: December 11, 1998
    Date of Patent: March 14, 2000
    Assignee: Ericsson, Inc.
    Inventors: Richard W. Farrington, Jun Zhang, William Hart
  • Patent number: 6025999
    Abstract: A power supply and a method of operating the same. In one embodiment, the power supply includes: (1) a DC-DC converter having an isolation transformer that conveys an alternating voltage of about a first frequency between a primary winding and at least one secondary winding thereof and (2) a four-quadrant inverter, coupled to one of the at least secondary winding, that converts a portion of the alternating voltage into a waveform having about a second frequency that is less than the first frequency, including: (2a) a bi-directional switch, coupled between an input and an output of the four-quadrant inverter and (2b) a controller, coupled to the switch, that activates the switch to couple the input to the output during a portion of a switching cycle of the alternating voltage to change voltages in the waveform.
    Type: Grant
    Filed: November 12, 1998
    Date of Patent: February 15, 2000
    Assignee: Lucent Technologies Inc.
    Inventors: Richard W. Farrington, Mark E. Jacobs, Hengchun Mao, Vijayan J. Thottuvelil
  • Patent number: 5991168
    Abstract: For use with a power converter having a main output and an auxiliary output and an auxiliary regulating switch that regulates a voltage at the auxiliary output, a transient response network, and method of diverting energy from the main output to the auxiliary output. In one embodiment, the transient response network, includes: (1) an energy diverting switch interposed between the main output and the auxiliary output, and (2) a control circuit, coupled to the energy diverting switch, that senses a characteristic of the power converter and causes the energy diverting switch to conduct a current in response to a substantial load reduction at the main output thereby diverting energy from the main output to the auxiliary output.
    Type: Grant
    Filed: May 5, 1998
    Date of Patent: November 23, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: Richard W. Farrington, Mark Elliott Jacobs
  • Patent number: 5991174
    Abstract: In a power converter having an input coupled to a power switch and a rectifier for conducting currents from the input to an output of the power converter, a snubber circuit for, a method of, moderating reverse recovery currents associated with the rectifier and a power converter employing the circuit or the method. In one embodiment, the circuit includes a snubber inductor and snubber capacitor coupled to the rectifier. The circuit further includes a first auxiliary switch that conducts to divert a portion of the currents away from the rectifier through the snubber inductor and snubber capacitor. The circuit still further includes a second auxiliary switch, interposed between the power switch and the first auxiliary switch, that conducts to create a path to discharge the capacitor to the output of the power converter.
    Type: Grant
    Filed: August 28, 1998
    Date of Patent: November 23, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: Richard W. Farrington, William P. Gardiner
  • Patent number: 5912549
    Abstract: For use with a power factor correction circuit, a current mode controller, a method of operating current mode control to achieve power factor correction thereof and a power supply incorporating the controller or the method. In one embodiment, the controller includes: (1) a modulator, coupled to a switch in the power factor correction circuit, that senses an electrical characteristic and a current passing through the power factor correction circuit and provides, in response thereto, a control signal to the switch and (2) a compensation circuit, coupled to an input of the power factor correction circuit, that provides a compensation signal to the modulator that is a function of a rectified line voltage provided to the input of the power factor correction circuit. The compensation signal causes the modulator to modify the control signal to reduce a total harmonic distortion (THD) of the power factor correction circuit.
    Type: Grant
    Filed: August 1, 1997
    Date of Patent: June 15, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: Richard W. Farrington, William P. Gardiner, Mark E. Jacobs, Hengchun Mao
  • Patent number: 5883793
    Abstract: For use with a power converter having first and second power switches coupled between a converter input and a primary winding of a transformer to impress an input voltage across the primary winding, a voltage clamp circuit for, and method of, resetting the transformer and a power converter employing the clamp circuit or the method. In one embodiment, the clamp circuit includes: (1) first and second reset windings coupled between the first and second power switches, (2) first and second energy storage devices coupled between the primary winding and the first and second reset windings, respectively, and (3) first and second switching circuits, coupled to the first reset winding and the second reset winding, respectively, that provide an electrical path from the primary winding to the converter input through the first and second reset windings, respectively, when the first and second power switches are not conducting.
    Type: Grant
    Filed: April 30, 1998
    Date of Patent: March 16, 1999
    Assignee: Lucent Technologies Inc.
    Inventor: Richard W. Farrington