William James Rader

US Patent:

60576073, May 2, 2000

Filed:

Jul 16, 1999

Appl. No.:

9/354630

Inventors:

William Edward Rader - Cary NC
John Fogg - Apex NC

Assignee:

Semtech Corporation - Newbury Park CA

International Classification:

H02J 100

US Classification:

307 11

Abstract:

A step-down switched-mode power supply circuit includes a transformer having at least one primary winding and at least one secondary winding, a current sensing device for sensing a current through a primary winding of the transformer, a first switch and a second switch, a first comparator for determining if the current through the current sensing device exceeds a threshold, a voltage regulator coupled to the secondary winding to produce a regulated voltage, a second comparator for determining if the regulated voltage has drooped below an acceptable level, a counter coupled to the second comparator for generating a signal having a fixed number of switch cycles, and control circuitry for generating signals controlling the first switch and the second switch and responsive to the first comparator to enter a power saving mode disabling the signals, and to the second comparator to temporarily exit the power saving mode for a fixed number of cycles when the regulated voltage has drooped below an acceptable level.

US Patent:

62395092, May 29, 2001

Filed:

Mar 30, 2000

Appl. No.:

9/539275

Inventors:

William Edward Rader - Cary NC
John Fogg - Apex NC

Assignee:

Semtech Corporation - Newbury Park CA

International Classification:

H02J 300

US Classification:

307 11

Abstract:

A step-down switched-mode power supply circuit includes a transformer having at least one primary winding and at least one secondary winding, a current sensing device for sensing a current through a primary winding of the transformer, a first switch and a second switch, a first comparator for determining if the current through the current sensing device exceeds a threshold, a voltage regulator coupled to the secondary winding to produce a regulated voltage, a second comparator for determining if the regulated voltage has drooped below an acceptable level, a counter coupled to the second comparator for generating a signal having a fixed number of switch cycles, and control circuitry for generating signals controlling the first switch and the second switch and responsive to the first comparator to enter a power saving mode disabling the signals, and to the second comparator to temporarily exit the power saving mode for a fixed number of cycles when the regulated voltage has drooped below an acceptable level.