TEMPERATURE DETECTING DEVICE OF POWER SWITCHING ELEMENT

摘要

PROBLEM TO BE SOLVED: To solve such a problem that a detection error is caused by an individual difference of an electric device connected to a temperature sensing diode SD and the like upon detection of the temperature of a power switching element Sw by the temperature sensing diode SD.SOLUTION: A current from a constant current source 14 is input to a cathode of a temperature sensing diode SD through a regulating resistor 20. An anode voltage of the temperature sensing diode SD is fed into a PWM comparator 16 through the regulating resistor 20. The PWM comparator 16 generates a time ratio signal according to the anode voltage of the temperature sensing diode SD based on the relative magnitude between the anode voltage of the temperature sensing diode SD and a carrier, and outputs it. The regulating resistor 20 is externally attached to a power card PC mounted with the temperature sensing diode SD, and used to regulate output signals from the PWM comparator 16.