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Switching Regulator with Transistor Turnoff

IP.com Disclosure Number: IPCOM000079825D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Palmucci, CJ: AUTHOR

Abstract

The circuit of the drawing supplies a load from a potential point 2 according to a pulse square wave that is applied to a transistor 3. A high-voltage transistor 4 is connected to be turned on and off by transistor 3, and it is connected to supply current to the load in its emitter circuit. A diode 6, an inductor 7, and a capacitor 8 help to filter the voltage waveform at the load.

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Switching Regulator with Transistor Turnoff

The circuit of the drawing supplies a load from a potential point 2 according to a pulse square wave that is applied to a transistor 3. A high-voltage transistor 4 is connected to be turned on and off by transistor 3, and it is connected to supply current to the load in its emitter circuit. A diode 6, an inductor 7, and a capacitor 8 help to filter the voltage waveform at the load.

A transformer 9 couples the collector circuit of transistor 3 to the base-emitter circuit of transistor 4. When transistor 3 is turned on, the secondary winding of the transformer supplies base current to transistor 4. Diodes 12 and 13 prevent transistor 4 from being saturated. When transistor 3 turns off, the voltage of a zener diode 14 appears across the transformer secondary winding in a direction opposite to the conduction of diode 12 and the forward current direction of the base-emitter junction of transistor 4. The voltage across diode 12 provides base current to turn on a transistor 16 which conducts between the base and emitter terminals of transistor 4, and thereby speeds up the removal of charge that is stored in this junction while transistor 4 is turned on. Thus, the circuit provides a low impedance in the forward direction of diode 12 for turning on transistor 4, and it provides a low impedance in the emitter collector circuit of transistor 16 for turning off transistor 4.

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