Patent ID: 7353133

Claim:
A multiple circuit overheating protection system for protecting against overheating of a CPU when an operation frequency is changed in accordance with a voltage variation of driving power, comprising: a CPU temperature sensor to detect a temperature of the CPU; a reference temperature sensor to detect a temperature of a circuit block heated due to the operation frequency of the CPU; a comparing part to output a signal of a higher temperature value obtained by comparing temperature values detected by the CPU temperature sensor and the reference part temperature determining sensor; and a CPU power supply to supply a stepwise decreasing driving power to decrease the operation frequency of the CPU in a stepwise fashion when the temperature value increases based on the signal for the higher temperature value outputted from the comparing part to provide overheating protection of the CPU and the circuit block, wherein the comparing part comprises: a comparing unit, to compare the temperature value of the CPU temperature sensor and the reference part temperature determining sensor to provide a temperature variation signal in accordance with a predetermined scheme; and a quantization unit, comprising: a micom having an A/D input pin to receive the temperature variation signal outputted from the comparing unit, and outputting a control signal as a digital driving signal; and a D/A converter, converting the digital driving signal to an analog driving signal supplied to the CPU power supply to enable the driving voltage power of the CPU to be decreased in a stepwise fashion when a temperature value increases, in accordance with the temperature variation signal.