This document specifies the 12 V and 24 V electrical physical layers (EPL) of the LIN communications system. The electrical physical layer for LIN is designed for low-cost networks with bit rates up to 20 kbit/s to connect automotive electronic control units (ECUs). The medium that is used is a single wire for each receiver and transmitter with reference to ground. This document includes the definition of electrical characteristics of the transmission itself and also the documentation of basic functionality for bus driver devices. All parameters in this document are defined for the ambient temperature range from −40 °C to 125 °C.