A semiconductor integrated circuit includes a digital-to-analog converter and a built-in self-test circuit. The digital-to-analog converter performs a normal conversion operation to generate an analog output signal by converting a digital input signal corresponding to an external digital signal that is provided from an external device outside the semiconductor integrated circuit and provide the analog output signal to the external device. The built-in self-test circuit, while the digital-to-analog converter performs the normal conversion operation, performs a real-time monitoring operation to generate a comparison alarm signal based on the digital input signal and the analog output signal such that the comparison alarm signal indicates whether the digital-to-analog converter operates normally. Performance and reliability of the digital-to-analog converter and the semiconductor integrated circuit including the digital-to-analog converter may be enhanced by monitoring in real-time abnormality of the digital-to-analog converter using the on-time monitor.