CMOS bidirectional transceiver/translator operating between two power supplies of different voltages

摘要

A signal level converting circuit for bidirectional transfer of logic signals between a first and second external logic circuit is disclosed. This signal level converting circuit is provided with a control circuit that generates control signals whose logic values can be arbitrarily set, and at least one bidirectional logic signal level converter. Each logic signal level converter is provided with first and second converting circuits. The first converting circuit is placed by the control signal of a first logic level into a high-impedance state that blocks the transmission of the logic signals between the two external logic circuits, and is placed by the control signal of a second logic level into a low- impedance state that allows transmission of logic signals, together with converting the logic signal level from a first signal level to a second signal level. The second converting circuit is placed by the control signal of the second logic level into a high- impedance state that blocks the transmission of the logic signals between the two external logic circuits, and is placed by the control signal of the first logic level into a low-impedance state that allows transmission of logic signals, together with converting the logic signal level from the second signal level to the first signal level.