In an optocoupler circuit, a first direction path, which transmits signals from a first to a second terminal, includes a first level shifter, a second level shifter, and a first optocoupler. The first level shifter receives a first input signal at the first terminal, and shifts a voltage level of the first input signal to a first shifted voltage level with respect to a first ground level in a first power domain, to provide a first shifted signal. The first optocoupler receives the first shifted signal, and generates a first optocoupler signal in response to the first shifted signal. The second level shifter receives the first optocoupler signal, and shifts a voltage level of the first optocoupler signal to a second shifted voltage level with respect to a second ground level in a second power domain, to provide a second shifted signal at the second terminal.