Title:
DC POWER SOURCE
Document Type and Number:
Japanese Patent JPS6378208
Kind Code:
A
Abstract:
PURPOSE:To realize a highly reliable DC power unit by switching to an excessive current protection circuit with a constant current dropping characteristic so as to activate it when a power source is turned on and switching to an excessive current protection circuit with a chevron-shaped characteristic once an output voltage exceeds a prescribed value after the activation. CONSTITUTION:Divided voltages from voltage division resistances 8 and 9 comprising the excessive current protection circuit with an angular-shaped characteristic are impressed on an error amplifier 7. If in that state a load attains an excessive current to the larger than the divided voltages of the voltage drop division resistances 8 and 9 in a current detection resistance 5, the excessive current signal of an output from a control circuit 7 inputs to an excessive current signal input terminal IS. Then a control circuit 3 operates to drop an output voltage detected from an output voltage terminal VS, and the excessive current protection with the angular-shaped characteristic works. By such an action, circuits rise by the excessive current protection circuit with a constant current dropping characteristic when the power source is turned on. If the output voltage exceeds a prescribed value, said protection circuit is switched to the one with the angular-shaped characteristic, and the power source and the load side are protected.
Inventors:
SENBA KAZUHISA
Application Number:
JP22186586A
Publication Date:
April 08, 1988
Filing Date:
September 22, 1986
Export Citation:
Assignee:
HITACHI LIGHTING LTD
International Classes:
G05F1/56; H02M3/00; (IPC1-7): G05F1/56
Domestic Patent References:
| JPS6140623A | 1986-02-26 |