ISO 17987-4:2025
(Main)Road vehicles — Local Interconnect Network (LIN) — Part 4: Electrical physical layer (EPL) specification 12 V/24 V
Road vehicles — Local Interconnect Network (LIN) — Part 4: Electrical physical layer (EPL) specification 12 V/24 V
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. Annex A provides recommendations on the LIN physical layer peripheral interface design of type UART and frame controller for commander and responder nodes. This document includes the definition of electrical characteristics of the transmission itself and also the documentation of basic functionality for bus driver devices. This document also provides the physical layer definitions for nodes with LIN AA capabilities according to one of the procedures C, D and E. All parameters in this document are defined for the ambient temperature range from −40 °C to 125 °C.
Véhicules routiers — Réseau Internet local (LIN) — Partie 4: Spécification de la couche électrique physique (EPL) 12V/24V
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 17987-4
Second edition
Road vehicles — Local Interconnect
2025-06
Network (LIN) —
Part 4:
Electrical physical layer (EPL)
specification 12 V/24 V
Véhicules routiers — Réseau Internet local (LIN) —
Partie 4: Spécification de la couche électrique physique (EPL)
12V/24V
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions .1
3.2 Symbols .2
3.3 Abbreviated terms .5
4 Conventions . 6
5 Electrical physical layer requirements . 6
5.1 Bit rate deviation .6
5.1.1 General .6
5.1.2 12 V LIN systems: parameters .6
5.1.3 24 V LIN systems: parameters .7
5.2 Timing requirements .9
5.2.1 Bit timing .9
5.2.2 Synchronization procedure .9
5.2.3 Bit sample timing .10
5.3 Line driver/receiver . 12
5.3.1 General configuration . 12
5.3.2 Definition of supply voltages for the physical interface . 12
5.3.3 Signal specification . 13
5.3.4 12 V LIN systems: electrical parameters .14
5.3.5 24 V LIN systems: Electrical parameters .18
5.3.6 Line characteristics .21
5.3.7 12 V LIN systems: performance in non-operation supply voltage range . 22
5.3.8 24 V LIN systems: performance in non-operation supply voltage range . 22
5.3.9 Performance during fault modes . 22
5.3.10 ESD/EMI compliance . 22
6 Procedures C, D and E . .23
Annex A (informative) LIN peripheral interface design considerations.24
Annex B (normative) LIN AA procedure C physical layer .29
Annex C (normative) LIN AA procedure D physical layer .32
Annex D (normative) LIN AA procedure E physical layer .39
Bibliography .43
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 31, Data
communication.
This second edition cancels and replaces the first edition (ISO 17987-4:2016), which has been technically
revised.
The main changes are as follows:
— master and slave terms used for the LIN node types in the ISO 17987 series are replaced within this
document with inclusive language terms commander and responder. This also applies for abbreviations
and file formats NCF and LDF;
— variables and formulae aligned with the ISO/IEC Directives, Part 2;
— updates of several parameter statements and requirements;
— various parameter values adopted in Annex C;
— editorial updates and several statements improved to avoid ambiguities.
A list of all parts in the ISO 17987 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
The LIN protocol as proposed is an automotive focused low speed universal asynchronous receiver
transmitter (UART) based network. Some of the key characteristics of the LIN protocol are signal-based
communication, schedule table-based frame transfer, commander/responder communication with error
detection, node configuration and diagnostic service transportation.
The LIN protocol is for low-cost automotive control applications as, for example, door module and air
conditioning systems. It serves as a communication infrastructure for low-speed control applications in
vehicles by providing:
— signal-based communication to exchange information between applications in different nodes;
— bit rate support from 1 kbit/s to 20 kbit/s;
— deterministic schedule table-based frame communication;
— network management that wakes up and puts the LIN cluster into sleep state in a controlled manner;
— status management that provides error handling and error signalling;
— transport layer that allows large amount of data to be transported (such as diagnostic services);
— specification of how to handle diagnostic services;
— electrical physical layer specifications;
— node description language describing properties of responder nodes;
— network description file describing behaviour of communication;
— application programming interface.
The ISO 17987 series is based on the open systems interconnection (OSI) basic reference model as specified
in ISO/IEC 7498-1 which structures communication systems into seven layers.
The OSI model structures data communication into seven layers called (top down) application layer (layer 7),
presentation layer, session layer, transport layer, network layer, data link layer and physical layer (layer 1). A
subset of these layers is used in the ISO 17987 series.
The ISO 17987 series distinguishes between the services provided by a layer to the layer above it and the
protocol used by the layer to send a message between the peer entities of that layer. The reason for this
distinction is to make the services, especially the application layer services and the transport layer services,
reusable also for other types of networks than LIN. In this way, the protocol is hidden from the service user
and it is possible to change the protocol if special system requirements demand it.
The ISO 17987 series provides all documents and references required to support the implementation of the
requirements related to the following.
— ISO 17987-1: provides an overview of the ISO 17987 series and structure along with the use case
definitions and a common set of resources (definitions, references) for use by all subsequent parts.
— ISO 17987-2: specifies the requirements related to the transport protocol and the network layer
requirements to transport the PDU of a message between LIN nodes.
— ISO 17987-3: specifies the requirements for implementations of the LIN protocol on the logical level of
abstraction. Hardware-related properties are hidden in the defined constraints.
— ISO 17987-4 (this document): specifies the requirements for implementations of active hardware
components which are necessary to interconnect the protocol implementation.
v
— ISO/TR 17987-5: specifies the LIN application programming interface (API) and the node configuration
and identification services. The node configuration and identification services are specified in the API
and define how a responder node is configured and how a responder node uses the identification service.
— ISO 17987-6: specifies
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