US 6,275,394 B1Granted

Input circuit

AssigneeOki Electric Industry Co., Ltd.

InventorsKazushige Matsuura, Shinichi Kouzuma

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Abstract

There is provided an input circuit with reduced electrical power consumption, which processes an input signal given thereto for removing the noise components contained therein and regulating the voltage level thereof as well, and then supplies an output signal therefrom to a subsequent semiconductor integrated circuit. The input circuit 101 is made up of the Schmitt buffer 111, a pull-down resistance 113, an N-transistor 115, a P-transistor 121, an N-transistor 122, a P-transistor 131, an N-transistor 132, an exclusive OR gate 141, and a bus driver 151. The Schmitt buffer 111 is a buffer which has two threshold levels i.e. upper and lower thresholds, and changes the level of the output signal OUT depending on whether the voltage of an input signal IN is higher or lower than these two threshold levels.

Claims13

Dependent claims

An input circuit which generates an output signal at its output node based on an input signal received at its input node, and supplies said output signal to an internal circuit according to an input/output control signal of the enable state, comprising:

a first voltage level production section which has an input terminal, an output terminal, a first power source terminal, and a second power source terminal, and produces a first voltage level, in response to a voltage level applied to said input terminal connected with said input node, based on a voltage level applied to said first power source terminal and a voltage level applied to said second power source terminal as well, and further supplies said first voltage level to an intermediate node;
a second voltage level production section which produces a second voltage level in response to the voltage level of said intermediate node, and supplies said second voltage level to said output node;
a voltage level comparison section which detects whether or not the voltage level of said output node coincides with the voltage level of said input/output control signal, and outputs a detection signal in correspondence with a detection result;
a voltage level holding section which holds a voltage level of said output node given at the time when said input/output control signal changes the state thereof from the enable state to the disable state;
and
a power source terminal selection section which makes either the first or second power source terminal of said first voltage level production section be in the high impedance state according to said detection signal put out from said voltage level comparison section.

3 more elements

Dependencies are inferred from the claim text.