The invention relates to the technical field of
circuit protection devices, in particular to a piezoresistor which comprises a packaging structure, a first pin, a second pin, a PTC
thermistor unit and a piezoresistor unit, the PTC
thermistor unit and the piezoresistor unit are packaged in the packaging structure, the second pin is electrically connected with the piezoresistor unit, and the first pin and the second pin are both partially exposed out of the packaging structure. The PTC
thermistor unit comprises a PTC thermistor
ceramic cavity, a first conductive part, a second conductive part and a
bimetal reed, the first conductive part and the second conductive part are electrically connected with the two opening ends of the PTC thermistor
ceramic cavity respectively and define a mounting cavity, and the
bimetal reed is arranged in the mounting cavity; one end of the
bimetal reed is fixedly and electrically connected with one of the first conductive piece and the second conductive piece, the other end of the bimetal reed is used as a movable contact to abut against the other one of the first conductive piece and the second conductive piece, the first conductive piece is electrically connected with the first pin, and the second conductive piece is electrically connected with the piezoresistor. The device is high in reliability and simple in structure.