Patent ID: 7542259

Claim:
A protection apparatus for providing thermal protection to an electronic system, comprising: a temperature detection module, configured for outputting a first voltage signal and a second voltage signal, wherein values of the first and second voltage signals vary with a variation of ambient temperature, the temperature detection module comprising: a current mirror circuit configured for generating a first current signal, and a second current signal having a value substantially same as that of the first current signal, the current mirror circuit comprising: a control unit, comprising: a third PMOS transistor, comprising a source coupled to the voltage source, a gate electrically coupled to the gate of the second PMOS transistor, and a drain and the gate of the third PMOS transistor are electrically connected together; and a resistor having one end thereof electrically coupled to the drain of the third PMOS transistor, and another end thereof grounded; a first PMOS transistor, comprising a source coupled to a voltage source, a gate electrically coupled to the control unit and a drain electrically coupled to one end of the positive temperature coefficient resistor, for outputting the first current signal to the positive temperature coefficient resistor; and a second PMOS transistor, comprising a source coupled to the voltage source, a gate electrically coupled to the gate of the first PMOS transistor and a drain electrically coupled to one end of the negative temperature coefficient resistor, for outputting the second current signal to the negative temperature coefficient resistor; a positive temperature coefficient resistor, wherein one end of the positive temperature coefficient resistor is grounded, and another end of the positive temperature coefficient resistor is configured for receiving the first current signal for generating the first voltage signal; and a negative temperature coefficient resistor, wherein one end of the negative temperature coefficient resistor is grounded, and another end of the negative temperature coefficient resistor is configured for receiving the second current signal for generating the second voltage signal; and a comparator unit, configured for comparing the first voltage signal with the second voltage signal to generate and transmit a protection signal to the electronic system to determine whether or not to allow the electronic system to operate normally.