Patent ID: 8217660

Claim:
An open terminal detection device that detects an open terminal and a recovery from said open terminal, comprising: a diode; a transistor that is supplied with a base current from a current source through the diode that limits discharge of a base charge of the transistor, in which the base current decreases corresponding to an increase in an external impedance of the terminal, wherein the terminal is supplied by the current source; and an output circuit adapted to the transistor, the output circuit outputting an output signal in coordination with on/off switching of the transistor, wherein said diode is arranged such that on occurrence of an open terminal, a switching off of the transistor is prolonged, on occurrence of a recovery from an open terminal, a switching on of the transistor happens rapidly, and a time from a time of a recovery from an open terminal to a time of detection of said recovery is shorter than a time from a time of an occurrence of an open terminal to a time of detection of said open terminal.