Rohm Co., Ltd.

Hiroyoshi Ishida

Hideki Matsubara

Hiroki Yamakami

A switch state determining device, includes: an external terminal to which a switch is externally attached; a constant current generating part configured to generate a constant current and flow the constant current through the external terminal; a voltage comparing part configured to compare a terminal voltage of the external terminal with a threshold voltage to generate a comparison signal; an ON/OFF determining part configured to output an ON/OFF determination signal of the switch depending on the comparison signal; a threshold voltage control part configured to adjust the threshold voltage depending on a threshold voltage set value; and a level determining part configured to output a level determination signal of the terminal voltage or a terminal voltage value.

Switch state determining device

A switch monitoring device includes a constant current source which supplies a current to an input line or extracts a current from the input line, a switch which connects the input line to a supply voltage or to a ground voltage, a comparator which compares a voltage on the input line with a reference voltage, a logic which receives an output voltage of the comparator, a base current source which generates a base current, and a bias current circuit which generates a bias current by adjusting the base current as a base in accordance with a current control signal from the logic and the output voltage of the comparator. The constant current source generates a current by adjusting the bias current as a base.

Growing community of inventors

Kyoto, Japan

Hiroyoshi Ishida