A slave circuit of a LIN bus and method for operating a slave circuit is provided. The slave circuit includes a receiver circuit that is connected to the bus in order to output bit sequences as a function of a bus voltage, an interface circuit for controlling a sleep mode and a normal mode, a detector circuit for evaluating the bus voltage which is connected to the bus, a timer device that is connected to an output of the detector circuit and to the interface circuit. Whereby, the detector circuit, the timer device, and the interface circuit are designed to detect an exceedance of a time threshold by a waveform of the bus voltage of the bus, and to continue a sleep mode in the event of an exceedance, wherein the time threshold is greater than the duration of a wake-up command.