Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Reexamination Certificate
2003-05-08
2004-09-07
Riley, Shawn (Department: 2838)
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
C361S018000
Reexamination Certificate
active
06788514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to power supplies and, more specifically, the present invention relates to a switching regulator.
2. Background Information
In a switching power supply, a power supply controller is connected in series with a primary winding of a transformer to the high voltage direct current (DC) input derived from alternating current (AC) power line through rectification and filtering. Energy is transferred to the secondary winding in a manner controlled by the power supply controller so as to provide a constant output voltage. Another winding called a feedback or bias winding may be used to provide a feedback signal to the power supply controller. Alternatively, the feedback signal can come through an opto-coupler from a sense circuit at the secondary output. The feedback signal is used to modulate the duty cycle of the power supply controller or used to allow or disallow cycles in order to control the secondary output.
In the event of a short circuit condition, an overload condition (may be caused by either an overload at the output secondary winding or an under voltage condition at the power supply input) or an open in the feedback loop, the power supply controller detects the loss of feedback signal and goes into a mode called “auto-restart.” In the auto-restart mode, the power supply controller tries to start the power supply periodically by delivering power for a period of time, also known as the on-time, (greater than needed for start up) and turns off the power supply for another period of time, also known as the off-time. As long as the fault condition is present, the power supply controller remains in this auto-restart mode limiting the average output power to a safe, low value. When the fault is removed, auto-restart enables the power supply to start automatically.
The operating principle of auto-restart is to reduce the average power delivered to the power supply output during fault condition to a safe level by running the power supply alternately between a first predetermined time period (also known as on-time) and a second predetermined time period (also known as off-time). During on-time power supply is on delivering energy to output while during off-time power supply is off delivering no energy to output. To make auto-restart protection effective, the off-time is set significantly longer than the on-time. When fault condition occurs for a duration shorter than the auto-restart off-time, the power supply will not attempt to restart until the off-time is over resulting in unnecessary long delay before recovery.
SUMMARY OF THE INVENTION
Methods and apparatuses for fault condition protection of a switched mode power supply are disclosed. In one aspect of the invention, a power supply circuit having an auto-restart function to turn the power supply on and off repeatedly under fault conditions is included. In one embodiment, one or more off-times following detection of a fault condition is smaller than subsequent off-times. Additional features and benefits of the present invention will become apparent from the detailed description and figures set forth below.
REFERENCES:
patent: 4266259 (1981-05-01), Howell
patent: 4394703 (1983-07-01), Butcher
patent: 4685020 (1987-08-01), Driscoll et al.
patent: 4761702 (1988-08-01), Pinard
patent: 4887199 (1989-12-01), Whittle
patent: 4916573 (1990-04-01), Ruta
patent: 5264782 (1993-11-01), Newton
patent: 5510699 (1996-04-01), Theus et al.
patent: 5550437 (1996-08-01), Hopkins et al.
patent: 5698970 (1997-12-01), Stanojevic
patent: 5747978 (1998-05-01), Gariboldi et al.
patent: 5796596 (1998-08-01), Williams
patent: 5798635 (1998-08-01), Hwang et al.
patent: 5805401 (1998-09-01), Schuellein et al.
patent: 5874841 (1999-02-01), Majid et al.
patent: 5949154 (1999-09-01), Williams
patent: 6147883 (2000-11-01), Balakrishnan et al.
patent: 6154377 (2000-11-01), Balakrishnan et al.
patent: 6580593 (2003-06-01), Balakrishnan
patent: 02 25 1781 (2002-10-01), None
Ashok Bindra,“Power-Conversion Chip Cuts Energy Wastage in Off-Line Switchers,”Electronic Design, pp. 46, 48 (Oct. 1998).
Blakely , Sokoloff, Taylor & Zafman LLP
Power Intergrations, Inc.
Riley Shawn
LandOfFree
Method and apparatus for fault condition protection of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for fault condition protection of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for fault condition protection of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3234177