1 Introduction

An automotive battery connects to multiple loads, including electronic control units (ECUs), relays and motors. Several system-level events, such as turning inductive loads on or off, can create voltage transients along battery supply lines. All reverse-polarity protection circuits must protect downstream electronic loads against these system level transient events.

Ideal diode reverse-battery protection typically comprises of an ideal diode controller, N-channel metal-oxide semiconductor field-effect transistor (MOSFET) and an input-side transient voltage suppression (TVS) diode to clamp transient events. This TVS diode consumes as much as 70% of the solution footprint, however, which is a challenge when designing dense ECU designs such as automotive driver assistance system (ADAS) cameras, USB hubs and display ECUs. Removing the input-side TVS saves system cost, reduces solution size and improves system reliability.

This article describes a TVS-less reverse-battery protection system design using an ideal diode controller, analyzing the system architecture for protection and electromagnetic compliance (EMC) in accordance with International Organization for Standardization (ISO) 7637-2 and 16750-2, and original equipment manufacturer (OEM) standards such as VW8000 (LV124) from German auto manufacturers.