TRANSISTOR PROTECTION CIRCUIT AND SWITCH CIRCUIT

摘要

PROBLEM TO BE SOLVED: To reliably protect a transistor operating as a switch circuit. SOLUTION: A multiplier circuit 9 multiplies a drain-source voltageΔVx of a MOSFET Qm by a voltageΔVy across terminals of a resistor Rs to output a voltageΔVo corresponding to a power detection signal. A comparator 10 has an offset voltage corresponding to a reference level Va relating to an allowable drain loss Pd of the MOSFET Qm and outputs an off command signal to a drive circuit 8, if the voltageΔVo exceeds the offset voltage. COPYRIGHT: (C)2008,JPO&INPIT