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Active Transient Suppressor for Line Operated Switching Regulator

IP.com Disclosure Number: IPCOM000052963D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Driscoll, CD: AUTHOR [+2]

Abstract

This article describes a transient suppressor using active devices to limit transient voltages to levels below those at which switching regulator components would be damaged.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

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Active Transient Suppressor for Line Operated Switching Regulator

This article describes a transient suppressor using active devices to limit transient voltages to levels below those at which switching regulator components would be damaged.

The drawing illustrates a switching regulator in which a full-wave bridge rectifier 10 is connected to an AC source through a current limiting resistor 12. The voltage across the outputs of rectifier 10 is applied to a bulk capacitor 14 through a diode 16. An over-voltage sensing circuit 18 is connected in parallel with capacitor 14. A transient-suppressing circuit, consisting of a resistor 20 and an SCR 22, is connected directly across the outputs of the rectifier 10. The control circuit for the transient-suppressing circuit includes a transistor 24 having its base connected to the over-voltage sensing circuit 18. A bias resistor 26 provides a current path from the upper end of capacitor 14.

As long as the output or bulk voltage Vb is at or below a predetermined level, transistor 24 remains on, grounding the gate of the SCR 22. Under normal conditions, the total output of the rectifier circuit 10 is applied across capacitor
14.

If a line transient increases the voltage across capacitor 14 beyond the predetermined level, over-voltage sensing circuit 18 drives transistor 24 off. Bias current supplied through resistor 26 triggers SCR 22 into conduction. Resistors 12 and 20 act as a voltage divider to reduce the voltage at the output side of the rectifier circuit. The diode 16 will be backbiased under these conditions since the voltage across capacito...