The class-D amplifier must maintain sufficient output power to drive the speaker to the specified audio level with sufficient audio quality. The amplifier must also have high efficiency and good EMI and EMC performance. In addition, many eCall systems require speaker diagnostics and IC protection circuitry.

Class-D amplifiers are used because of excellent efficiency, which is critical in the eCall application. The high efficiency is achieved by using metal-oxide semiconductor field-effect transistors (MOSFET) that switch to drive a bridge-tied load. However, the switching causes more electromagnetic radiation than other classes of amplifiers. Texas Instruments has several class-D amplifiers that use BD mode modulation, which reduces the ripple current that flows through the inductor. This improves the EMC performance and uses smaller components. This design is tested for radiated emissions according to CISPR-25.

Diagnostic and protection coverage is needed for eCall applications because of the unknown nature of the environment after a collision. If a speaker is faulty after a collision, the information can be sent to the call center so that the center knows that the speaker does not work. This coverage also helps to retrieve load diagnostics before there is a collision so that any problems with the system can be fed back to the driver for maintenance. Within the eCall module, it is unlikely for there to be an exposure to a high-voltage event. However, the connectors leaving the eCall module are in danger. Specifically, the speaker cables that connect the speaker to the eCall module can be connected to ground or battery during installation, maintenance, or during an accident. While no class-D amplifier can operate while such a condition is maintained on the output lines, without protection, even a momentary incident can damage a class-D amplifier. The TAS5441-Q1 has integrated protection for these events, reducing the need for external components, and the device can report problems over I²C. Damage can also occur to the class-D amplifier on the power supply input. Because the amplifier has to drive several watts on the output speaker, it is beneficial to power an audio amplifier directly from the battery. However, most class-D amplifiers cannot survive common battery conditions that can occur on the battery line. The TAS5441-Q1 integrates the protection necessary to survive a 40V load dump, which means that the only external protection necessary when operating off of the battery is a reverse battery protection diode.