Protection device and circuit protection apparatus containing the same

A circuit protection apparatus, comprising:

• a protection device, comprising:
• a substrate having a surface provide with a first electrode and a second electrode;
• a fusible element disposed on the substrate and connecting to the first electrode and the second electrode at two ends, the fusible element comprising a first metal layer and a second metal layer, the second metal layer being disposed on the first metal layer, the second metal layer having a melting point lower than that of the first metal layer, the second metal layer being at least 40% and less than 60% of the fusible element in thickness;
• and
• a heating element disposed on the substrate,
• wherein the protection device passes an over-voltage test where a current is applied to the heating element of the protection device to generate a power of 7 W-35 W such that the fusible element in a circuit is blown to open the circuit, and
• wherein the fusible element is blown within 10 seconds with the power of 7 W-35 W applied to the protection device;
• a detector senses a voltage drop or a temperature of the circuit to be protected;
• and
• a switch coupled to the detector to receive signals of the detector;
• wherein the switch turns on to allow current to flow through the heating element by which the heating element heats up to blow the fusible element when the detector senses the voltage drop or the temperature exceeding a threshold value.