Introduction

Originally published on Electronic Products

In recent conversations with auto manufacturers, 48V low-voltage rail has come up frequently. But why now? 48V systems aren’t new. They’ve helped improve efficiency and performance in mild hybrid electric vehicles (MHEVs) for years.

The renewed interest in 48V systems might have to do with the growing popularity of both battery electric vehicles (BEVs) and hybrid vehicles (HEVs). Electric or hybrid vehicles generating 48V off a high-voltage battery can realize an important benefit of 48V systems: adding a 48V low-voltage rail reduces the gauge of the wire harness that supplies power throughout the vehicle, and reduces the load current requirements of downstream semiconductor components such as power switches and motor drivers. Thus, 48V systems can deliver more power than 12V systems, opening up the opportunity to add features such as artificial intelligence or mini fridges.

BEV original equipment manufacturers (OEMs) are looking to optimize cost, weight and driving range for BEVs. From an electrical perspective, it’s possible to address all three by reducing wire harnesses through a zone architecture, as discussed in the Texas Instruments white paper, “How a Zone Architecture Paves the Way to a Fully Software-Defined Vehicle” or using a 48V low-voltage rail for power distribution. In the early 1900s, the automotive industry used a 6V rail to provide power, until the power demands of the electrical/electronic (E/E) systems forced the market to move to 12V. Now, today’s feature-rich vehicles are pushing the limits of 12V rail. There are challenges of moving from 12V to 48V, but also opportunities if OEMs move to adopt a 48V low-voltage rail.