LEVEL SHIFTER OUTPUT BUFFER CIRCUIT USED AS ISOLATION CELL

摘要

A level shifter output buffer circuit capable of being used as an isolation device is provided to shift a high voltage to a low voltage or a low voltage to a high voltage, and also to electrically isolate circuit regions with different operation voltages, by comprising a first level shifter and a second level shifter receiving an enable signal and a data signal. A level shifter output buffer circuit(100a) converts a first operation voltage into a second operation voltage and then outputs the second operation voltage to an output port. A first level shifter(22) receives an enable signal having one of the first operation voltage and the ground voltage. A second level shifter(24) receives a data signal having one of the first operation voltage and the ground voltage. A pull-up transistor(28) outputs the second operation voltage to the output port. A pull-down transistor(36) outputs the ground voltage to the output port. A first unit is connected between the first level shifter and the pull-up transistor, and controls to output the second operation voltage to the output port by making the pull-up transistor into a turn-on state in response to the data signal of the first operation voltage when the enable signal is enabled. A second unit is connected between the second level shifter and the pull-down transistor, and controls to output the ground voltage to the output port by making the pull-down transistor into a turn-on state in response to the data signal of the ground voltage when the enable signal is enabled. The first unit and the second unit make the pull-up transistor and the pull-down transistor into a turn-off state when the enable signal is disabled.