Patents by Inventor Kim Tung Cheng

Kim Tung Cheng 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: 6088247
    Abstract: A voltage clamp for a single-ended flyback converter provides partial leakage energy recovery and noise suppression. The voltage clamp is an improved version of a conventional RCD clamp. The voltage clamp includes two switches with different turn-off speeds. The voltage clamp includes a capacitor and two resistors. One resistor is connected in parallel with a capacitor and the other resistor is connected in parallel with the faster switch. The faster switch enables at least partial recovery of energy dissipated in a clamp resistor immediately after turn OFF of the slower switch. When the slower switch opens after the faster switch closes, noise in the circuit is suppressed by a damping resistor which remains effectively in a current path after the faster switch has re-opened.
    Type: Grant
    Filed: May 26, 1999
    Date of Patent: July 11, 2000
    Assignee: PI Electronics (H. K.) Limited
    Inventor: Kim Tung Cheng
  • Patent number: 5991171
    Abstract: A DC-to-DC converter is described that provides resonant-transition switching by ensuring that the voltage across a first switch falls to zero between cycles.
    Type: Grant
    Filed: February 5, 1998
    Date of Patent: November 23, 1999
    Assignee: PI Electronics (H.K.) Ltd.
    Inventor: Kim Tung Cheng
  • Patent number: 5986905
    Abstract: A voltage clamp for a single-ended flyback converter provides partial leakage energy recovery and noise suppression. The voltage clamp is an improved version of a conventional RCD clamp. The voltage clamp includes two switches with different turn-off speeds. The voltage clamp includes a capacitor and two resistors. One resistor is connected in parallel with a capacitor and the other resistor is connected in parallel with the faster switch. The faster switch enables at least partial recovery of energy dissipated in a clamp resistor immediately after turn OFF of the slower switch. When the main switch opens after the faster switch closes, noise in the circuit is suppressed by a damping resistor which thereby remains effectively in a current path after the faster switch has re-opened.
    Type: Grant
    Filed: October 29, 1997
    Date of Patent: November 16, 1999
    Assignee: PI Electronics (H.K.) Limited
    Inventor: Kim Tung Cheng