Patent ID: 7994841

Claim:
A dual temperature control circuit, comprising: a detection circuit operable to detect a first temperature of a first location and a second temperature of a second location, transform the first temperature to a first voltage signal, and transform the second temperature to a second voltage signal; a selection circuit operable to compare the first voltage signal and the second voltage signal to output a third voltage signal according to the comparison, the selection circuit comprising: a first comparator with a non-inverting input operable to receive the first voltage signal from the detection circuit and an inverting input operable to receive the second voltage signal from the detection circuit, wherein the first comparator compares the first voltage signal and the second voltage signal to output a first high voltage level signal when the first voltage signal is greater than the second voltage signal, or output a first low voltage level signal when the first voltage signal is less than the second voltage signal; a first N-type field effect transistor (N-FET) with a gate connected to an output of the first comparator and a drain operable to receive the first voltage signal from the detection circuit, wherein the first N-FET turns on according to the first high voltage level signal from the output of the first comparator so as to output the first voltage signal via a source of the first N-FET, or cuts off according to the first low voltage level signal from the output of the first comparator; and a P-type field effect transistor (P-FET) with a gate connected to the output of the first comparator, a drain operable to receive the second voltage signal from the detection circuit, and a source connected to the source of the first N-FET, wherein the P-FET cuts off according to the first high voltage level signal from the output of the first comparator, or turns on according to the first low voltage level signal from the output of the first comparator so as to output the second voltage signal via the source of the P-FET; and a control circuit connected to the selection circuit, operable to control a controlled circuit according to the third voltage signal output from the selection circuit.