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Switching Regulator With No Choke

IP.com Disclosure Number: IPCOM000047330D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Derdall, BC: AUTHOR

Abstract

A preregulation circuit is disclosed. The circuit provides a coarse preregulation voltage output of a relatively small voltage within a specified range for use in logic circuits. It also provides a larger output voltage for driving a main load such as a stepping motor. Preregulation is achieved without the bulk of conventional switching regulator or the inefficiency of a series regulator. Basic operation of the circuit shown in Fig. 1 is that the pass transistor Q2 is turned off when the input voltage is above a preset level. Transistor Q1 drives transistor Q2 to charge capacitor C2 until voltage Vin minus voltage Vref is equal to Vp of transistor Q1 . At this point Q1 is cut off, switching Q2 off and preventing any additional charging of C2 until voltage Vin drops back down. As shown in Fig.

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Switching Regulator With No Choke

A preregulation circuit is disclosed. The circuit provides a coarse preregulation voltage output of a relatively small voltage within a specified range for use in logic circuits. It also provides a larger output voltage for driving a main load such as a stepping motor. Preregulation is achieved without the bulk of conventional switching regulator or the inefficiency of a series regulator. Basic operation of the circuit shown in Fig. 1 is that the pass transistor Q2 is turned off when the input voltage is above a preset level. Transistor Q1 drives transistor Q2 to charge capacitor C2 until voltage Vin minus voltage Vref is equal to Vp of transistor Q1 . At this point Q1 is cut off, switching Q2 off and preventing any additional charging of C2 until voltage Vin drops back down. As shown in Fig. 2, Q2 conducts during the period when the input voltage is above Vc2 and below transistor Q1 voltage threshold. Loading of input voltage by current through transistor Q2 provides positive feedback through resistor R2 to produce very rapid switching of transistor Q2 . Capacitor C1 provides high frequency decoupling. Resistor R3 insures proper switching of transistor Q1 by providing a small load to prevent the negative slope from being delayed by stray capacitance. If the full-wave power filter, consisting of compacitor C3 and isolation diode D1, is not used, then some type of spike suppression would be required to prevent damage to transistor...