Early AC Line Failure Detection for Power Supplies
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
Primary AC voltage levels are monitored inexpensively to provide advanced warning of power line failure by comparing rectified DC output against a reference level voltage. The early warning of a failure allows corrective steps, such as storage of volatile information, switching of backup power systems, and the like. Fig. 1 is a power system modified to include early failure detection as used for a flyback regulator. Diodes CR1-CR4 rectify the AC line voltage from power source 10 to produce DC output across bulk filter capacitor 12. Switch 15 is an electronic switch (e.g., transistor, FET, etc.) pulse-width modulated under control of regulator 16 electronics, as is conventional for switched power supplies. Positive regulated output is produced at output terminal 17, while negative regulated output is at 18.