ISO 7637

ISO 7637 is a series of international standards published by the International Organization for Standardization (ISO) that specifies conducted transient disturbances on electrical equipment installed in passenger cars and light commercial vehicles. It defines test methods and requirements for the electrical compatibility of equipment when subjected to voltage transients caused by various events in the vehicle's electrical system.

The primary objective of ISO 7637 is to ensure that electrical and electronic devices in vehicles are robust and immune to disturbances such as load dumps, ignition coil interruption, and other voltage variations that can occur during normal operation. These transients can potentially damage or disrupt the functionality of sensitive electronic components.

The standards within the ISO 7637 series are typically broken down into parts, each addressing specific types of transient phenomena or application areas. These parts may cover topics such as:

• Part 1: Definitions and general considerations.
• Part 2: Electrical transient conduction along supply lines only.
• Part 3: Electrical transient transmission by capacitive and inductive coupling via lines other than supply lines.
• Part 4: Electrical fast transient/burst immunity test.
• Part 5: Functional status classification (FSC).

Each part of ISO 7637 defines specific test pulses (e.g., pulse 1, pulse 2a, pulse 3a/3b, pulse 4) with defined voltage levels, durations, and source impedances. These pulses are designed to simulate different types of transients that might occur in the vehicle environment. The standard specifies how these test pulses are applied to the equipment under test (EUT) and the performance criteria that the EUT must meet to pass the test. Performance criteria typically involve the EUT maintaining its intended functionality during and after the application of the test pulse.

Conformance to ISO 7637 is often a requirement for automotive manufacturers and suppliers to ensure the reliability and safety of their products. By adhering to these standards, manufacturers can minimize the risk of electrical malfunctions and ensure the proper operation of electronic systems in vehicles.