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Current Control and Limiter Circuit

IP.com Disclosure Number: IPCOM000091496D
Original Publication Date: 1968-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Franz, FK: AUTHOR [+2]

Abstract

The circuit receives an unregulated voltage at terminal 2 and produces at output terminal 3 a current that is limited to a preselected value. The circuit is useful for supplying current pulses to a magnetic memory having inductive load 4 that is switched by transistor 5 in response to an address signal.

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Current Control and Limiter Circuit

The circuit receives an unregulated voltage at terminal 2 and produces at output terminal 3 a current that is limited to a preselected value. The circuit is useful for supplying current pulses to a magnetic memory having inductive load 4 that is switched by transistor 5 in response to an address signal.

The network of transistors 6 and 7 and resistor 8 is connected to draw current through series load resistor 9. Transistor 12 is connected with resistors 13 and 14 to control transistors 6 and 7 according to the difference between the voltage across resistor 9 and the voltage across emitter resistor 13. The voltage across resistor 9 is proportional to the current that is to be regulated. The voltage across resistor 13 is limited by a network comprising transistors 15 and 16, diode 18, and associated resistors.

When transistor 5 is turned on, current rises in resistor 9 and transistor 12 conducts at a low level in circuit with resistors 13 and 14. Because resistor 14 is connected to a point more negative than ground, transistors 6 and 7 do not turn on. At the preselected current level, the voltage across resistor 14 is at a level to turn on transistors 6 and 7 and thus oppose a further increase in the current through inductor 4. The voltage across resistor 13 is at a level to turn on diode 18 to thus supply emitter circuit to transistor 12 independently of resistor 13. Thus the circuit provides regulation at the preset current lev...