External Load Diagnostics for Automotive Class-D Amplifiers (.PDF Download)

Embedded electronics has continued to ramp up across the automotive landscape, taking on more substantial roles in many applications. One example is the presence of multiple class-D audio amplifiers within the system to implement radios, Bluetooth connections, and the like.

With greater dependence on electronic systems comes an increasing need to monitor their operation in order to detect potentially critical failures. Such monitoring can be done with load-diagnostic circuitry, which identifies potential faults that may occur in electrical circuitry throughout an automobile. This article explores the design of external fault-diagnostic circuitry intended to differentiate between various short-circuit conditions and provide speaker detection.

Another issue of concern is the increase in electromagnetic interference (EMI) within the vehicle. Innovative circuit design can help with this problem: For instance, a new four-channel class-D amplifier IC introduced in this article specifically takes on that challenge.

Common Faults

Most automotive audio systems use class-D switching amplifiers to operate the multiple speakers. Damage can easily result from improper interconnections or from valid faults in the equipment. The most common faults involve the misconnection of the class-D amplifier outputs and their speakers during manufacturing, testing, or servicing.