Denso Corporation

Nippon Soken, Inc.

Hiroyuki Obata

Tomohisa Kishigami

Youichirou Suzuki

Noboru Maeda

Masakiyo Horie

Masahiro Kitagawa

Hideaki Ishihara

Hiroyuki Mori

Tomoyuki Koike

Katsuhito Takeuchi

A ringing suppression circuit for a communication circuit that performs communication through a transmission line includes a high side switch connected between a high potential reference point and a high side line of the transmission line, a low side switch connected between a low potential reference point and a low side line of the transmission line, and a ringing suppression section. The ringing suppression section turns on the high side switch based on a difference between a potential of the high side line and a potential applied to a control terminal of the high side switch. The ringing suppression section turns on the low side switch based on a difference between a potential of the low side line and a potential applied to a control terminal of the low side switch.

Ringing suppression circuit

An inter-line switching element formed of a MOSFET is provided between a pair of signal lines. When the level of a differential signal changes from high to low, a control circuit turns on the FET for a fixed period thereby to suppress ringing by decreasing the impedance between the signal lines when the level of the differential signal transitions, and causing the energy of the distortion of the differential signal waveform to be absorbed by the on-resistance of the FET.

A ringing suppression circuit for a communication circuit that performs communication through a transmission line includes a high side switch connected between a high potential reference point and a high side line of the transmission line, a low side switch connected between a low potential reference point and a low side line of the transmission line, and a ringing suppression section. The ringing suppression section turns on the high side switch based on a difference between a potential of the high side line and a potential applied to a control terminal of the high side switch. The ringing suppression section turns on the low side switch based on a difference between a potential of the low side line and potential applied to a control terminal of the low side switch.

An operation switching circuit switches over two comparators, which receives communication data, in accordance with a normal mode and a standby mode of a microcomputer. A delay circuit delays a mode switching signal. The mode switching signal and the delayed signal are combined by an OR gate and an AND gate to two comparator control signals, which have different high level periods. The comparators are driven by the comparator control signals, while a multiplexer is driven by the delayed signal. When one comparator is switched from the inoperative state to the operative state, the other comparator is continued to be held operative for the delay period before being switched to the inoperative state.

Comparator switching apparatus and method

A microcomputer prevents an unnecessary signal from being outputted before the microcomputer is released from a reset state when the microcomputer includes a plurality of circuit blocks operating at different power source voltages. A reset signal transmitted to an input/output terminal unit of the microcomputer is generated by carrying out an OR operation between reset signals transmitted to a 3 V system circuit unit and a 5 V system circuit unit by an OR gate.

Growing community of inventors

Nukata-gun, Japan

Hiroyuki Obata