Hitachi, Ltd.

Kouji Masui

Tsutomu Yamada

Kenichi Kurosawa

Yasuo Kaminaga

Akihiro Ohashi

Input/output device for connection and disconnection of active lines

There is provided an input/output device having of not exerting any adverse influence on other expansion devices connected to a system bus at the time of insertion or removal. An expansion device,comprises an electronic circuit,and a MOS switch,and is connected to a system bus (BUS) via a connector having long and short pins. The expansion device,two power supply systems, namely a stable power supply,and an unstable power supply,At the time of insertion or removal of the expansion device,power is provided to the MOS switch,and a high impedance maintaining circuit from the stable power supply via a pair of long pins, so as to reliably place the MOS switch,in a high impedance state, inside the expansion device the high impedance maintaining circuit,drives an open/close control terminal, and power is provided to the electronic circuit,from the unstable power supply,At the time of insertion or removal, adverse influence is not exerted on the signal transmission on the system bus, and effects of load variation on the main power supply are reduced.

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Hitachi, Japan

Kouji Masui