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Patent Searching and Data


Title:
INDUCTIVE LOAD DRIVE CIRCUIT
Document Type and Number:
Japanese Patent JPS634605
Kind Code:
A
Abstract:

PURPOSE: To prevent an inductive load to be overheated abnormally by providing an integrating circuit on the input side of a comparator for controlling a voltage to the integrating circuit.

CONSTITUTION: A voltage is applied to an inductive load 3 for a period of time T through a driving transistor 4, so that a voltage is produced across a current detecting resistance 5. A transistor 11 in an integrating drive circuit is turned ON and an integrating capacitor 9 is discharged through the integrating resistor 8 to a voltage VT as indicated by the point 30 on the curved line 21 in the figure. If voltage application lasts past time T, the integrating capacitor 9 continues to discharge below the voltage VT. If the voltage is lower than a reference voltage VREF, the comparator 7 is inverted to open a switch 2 and thereby to stop supplying power to the inductive load 3. In this manner, the inductive load 3 is effectively prevented from being excessively heated by power loss.


Inventors:
Ishizaki, Sunao
Application Number:
JP1986000147044
Publication Date:
January 09, 1988
Filing Date:
June 25, 1986
Export Citation:
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Assignee:
NEC CORP
International Classes:
H01F7/18; (IPC1-7): H01F7/18