LSI device capable of adjusting the output impedance to match the characteristic impedance

Abstract

According to an aspect of the present invention there is provided an LSI device having an output terminal outputting a data, comprising a data output circuit connected to the output terminal and capable of adjusting an output impedance thereof; and an adjustment circuit which detects a transient voltage at the output terminal when an output logic of the data output circuit is switched in a condition that a transmission line not terminated by a terminating resistor is connected to the output terminal, compares the transient voltage with a reference voltage, and adjusts the output impedance of the data output circuit so as to match a characteristic impedance of the transmission line. According to the present invention, as the transient voltage of the output terminal connected to the transmission line is detected, and the output impedance of the data output circuit is adjusted, it is possible to adjust so that output impedance of the data output circuit is matched with characteristic impedance of the transmission line even if manufacture processes, use temperatures, power supply voltages, characteristic impedance of the transmission line, or the like fluctuates or is changed.

Dependencies are inferred from the claim text.