| 摘要 |
PROBLEM TO BE SOLVED: To protect an intelligent power switch IPS by detecting overcurrent of the IPS and interrupting MOSFET(MOS-type field effect transistor) when an overcurrent flows. SOLUTION: The intelligent power switch IPS is provided with a power supply use overheat self-interrupt type semiconductor switch QA that switches power supplied from a power supply 4, a series circuit that consists of a reference use overheat self-interrupt type semiconductor switch QB, having the same voltage characteristic as that of the switch QA and a reference resistor Rr1 and is connected in parallel with the switch QA, a comparison circuit CMP1, that compares the difference (A-B) between the source voltage A of the switch QA and the source voltage B of the switch QB with a prescribed over-current criterion value C so as to discriminate whether this is an overcurrent and outputs a detection signal in response to the result of discrimination, and a drive circuit 2 that turns on/off the overheat self-interrupt type semiconductor switch QA with a control signal in response to the detection signal.
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