Rohm Co., Ltd.

Hiroki Yamakami

Satoshi Tanaka

Toru Mukai

Hideki Matsubara

Hiroyoshi Ishida

Shinya Masuda

A communication system is configured to use a pulse width modulation signal as transmission code among a plurality of nodes connected to a communication line. A master node includes a transmission transistor connected to the communication line, a detector configured to detect a variation in current during the on-period of the transmission transistor, and a communication circuit configured to determine the off-timing of the transmission transistor based on the timing of occurrence of the variation in current (i.e., the on-timing of a second transmission transistor provided in a slave node). For example, the communication circuit can be configured to determine the off-timing of the transmission transistor such that the simultaneously-on period TB of the transmission transistor and the second transmission transistor fulfills TB=(2n−1)/2f, where f is the frequency of EMI noise.

Communication device and communication system

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.

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Kyoto, Japan

Hiroki Yamakami