초록 ▼

A temperature detecting circuit detects the rise of ambient temperature, using a forward voltage drop across a diode. The temperature detecting circuit comprises a temperature detecting diode whose cathode is grounded, a first constant current supply device connected with the anode of the temperatur

A temperature detecting circuit detects the rise of ambient temperature, using a forward voltage drop across a diode. The temperature detecting circuit comprises a temperature detecting diode whose cathode is grounded, a first constant current supply device connected with the anode of the temperature detecting diode, for supplying a constant current Ia to the temperature-detecting diode, a rectifying diode whose cathode is connected with the anode of the temperature detecting diode, a second constant current supply device connected with the anode of the rectifying diode, for supplying a constant current Ib to the temperature-detecting diode, a comparator, and a transistor. When the voltage at the anode of the temperature-detecting diode is lower than a reference voltage, the comparator produces a high-level signal indicative of overheating. In response to this, the transistor shorts the anode of the rectifying diode to ground potential to supply the constant current Ib from the second constant current supply device directly to ground potential.

대표청구항 ▼

[ What is claimed is:] [1.] A temperature detecting circuit for detecting the rise and ambient temperature by making use of forward voltage drop produced across a diode, said temperature-detecting circuit comprising:a first constant current supply device connected in series with said diode, for supp

[ What is claimed is:] [1.] A temperature detecting circuit for detecting the rise and ambient temperature by making use of forward voltage drop produced across a diode, said temperature-detecting circuit comprising:a first constant current supply device connected in series with said diode, for supplying a first constant current to said diode;a second constant current supply device connected in parallel with said first constant current supply device and in series with said diode, for supplying a second constant current to said diode;a voltage-detecting circuit for detecting said forward voltage drop across said diode and producing an output signal indicating overheating when said forward voltage drop is smaller than a predetermined value; anda bypass circuit for bypassing said second constant current supplied from said second constant current supply device around said diode when said voltage detecting circuit is producing said output signal.