Reliable Electrical Load Driving Strategy with 24V Truck BCM

Recent years have witnessed an increase in the number of electrical loads being driven by semiconductor devices in the body control module (or BCM) rather than by electro-mechanical relays in a typical truck with a 24V vehicle power net. This paper presents the major challenges caused by the higher voltage class of the truck supply and the longer wire harness cables, followed by an analysis of some key issues related to the design of truck BCMs to drive different loads. It offers some general guidance on practical design issues to BCM designers, such as an understanding of the advantages and disadvantages of different BCM architectural topologies, how to make a choice between a relay or a semiconductor driver, knowledge of the requirements of semiconductors used in truck applications etc. Finally a reference design of a truck BCM is presented to showcase how to achieve the system specifications and goals which includes comprehensive protection and diagnostic features while maintaining a great degree of design flexibility.