ISO 17987-4:2025

Overview

ISO 17987-4:2025 - Road vehicles - Local Interconnect Network (LIN) - Part 4: Electrical physical layer (EPL) specification 12 V/24 V defines the electrical physical layer for LIN networks used in automotive systems. It specifies the 12 V and 24 V EPLs used for low-cost single-wire communication between electronic control units (ECUs) with bit rates up to 20 kbit/s. The standard covers electrical characteristics of transmission, basic bus-driver functionality, and physical layer variants for nodes with LIN AA capabilities (procedures C, D and E). All parameters apply across the automotive ambient range of −40 °C to 125 °C.

Key topics and technical requirements

The document addresses practical and testable EPL requirements, including:

• Bit rate deviation and tolerance definitions for BR_Range_20K and BR_Range_10K systems (up to 20 kbit/s).
• Timing requirements: bit timing, synchronization procedures and bit sampling timing for reliable UART-based LIN communication.
• Line driver and receiver specifications: supply voltage definitions, signal specifications and bus-driver basic functionality for both 12 V and 24 V systems.
• Line characteristics and bus capacitance considerations for single-wire networks referenced to ground.
• Performance during fault modes and non-operation supply voltage ranges to ensure robustness in automotive environments.
• ESD/EMI compliance references (normative reference includes IEC 61000-4-2).
• LIN AA procedures C, D, E - normative annexes defining physical layer behaviour for advanced node capabilities.
• Annex A (informative): recommendations for LIN peripheral interface design (UART and frame controller) for both commander and responder nodes.

Practical applications - who uses this standard

ISO 17987-4:2025 is essential for organizations designing, validating or integrating LIN physical layer hardware and systems:

• Automotive ECU hardware and transceiver manufacturers (12 V / 24 V LIN transceivers and bus drivers).
• Vehicle system architects and network integrators implementing LIN clusters for body electronics (doors, HVAC, seats, lighting).
• Embedded firmware and UART peripheral designers implementing LIN commander and responder behaviour.
• Test laboratories and compliance engineers performing conformance testing and EMC/ESD validation.
• Tier-1 suppliers and OEMs specifying LIN EPL requirements for robust in-vehicle communication.

Related standards

• ISO 17987-1: General information and use cases (LIN series overview)
• ISO 17987-2, -3: Transport and logical protocol requirements
• ISO 17987-5: LIN API and node configuration
• ISO 17987-6, -7: Conformance tests and EPL testing
• IEC 61000-4-2: ESD immunity testing

ISO 17987-4:2025 is the authoritative reference for implementing the LIN electrical physical layer (12 V/24 V), ensuring interoperability, durability and predictable behaviour across automotive ECUs and LIN networks.