OVERCURRENT PROTECTIVE CIRCUIT

PURPOSE:To reduce a power loss and miniaturize a device and lower a cost by connecting current detecting means to the respective three power elements on the lower arm side, in parallel with each other. CONSTITUTION:Current sense MOSFETs Q7, Q8 and Q9 are activated on the same timing as that of corre...

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Bibliographische Detailangaben
Hauptverfasser: FUKUNAGA MASANORI, MAJIYUUMUDAARU GOORABU
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:PURPOSE:To reduce a power loss and miniaturize a device and lower a cost by connecting current detecting means to the respective three power elements on the lower arm side, in parallel with each other. CONSTITUTION:Current sense MOSFETs Q7, Q8 and Q9 are activated on the same timing as that of corresponding power MOSFETs Q2, Q4, and Q6 on the lower arm side, and to corresponding detecting resistors Rs1, Rs2 and Rs3 for diverting main current, detecting current is permitted to flow. When overcurrent is generated on the power MOSFETs Q2, Q4 and Q6, then voltage drop detecting point SU, SV and SW potentials acoording to the power MOSFETs are turned higher than reference voltage Vref1. Then, the output of comparators COM1, COM2 and COM3 according to the potentials comes to a level 'H', and accordingly, the output of logical sum logics OR1, OR3, also comes to a level 'H', and abnormal state signal Fault is issued. Because of a composition for diverting the main current as mentioned above, a power loss for detection is sufficiently reduced.