Buck controller adds sound quality and efficiency to STMicroelectronics automotive amplifier

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STMicroelectronics has announced that its latest TDA7901 automotive amplifier integrates a buck controller for class-G power switching and supports high-definition audio, which it states is a market-unique combination that provides a great listening experience combined with high efficiency.

In class-G operation, the buck controller automatically optimizes the voltage supplied to the bridge-tied load (BTL) power stage depending on the audio-signal level. The resulting smooth, analog sound comes with near-class-D efficiency at normal listening levels; because the power dissipation is much lower compared to a conventional class-A/B amplifier, the heatsink requirement is optimized. Integrating the buck controller in the IC contributes to reducing system size and weight. It also cuts the bill of materials, simplifies circuit design, and saves developing firmware to control the voltage rail.

The company states that the TDA7901 is suited to use in many in-vehicle information (IVI) systems, such as head units, smart cockpit systems, external amplifiers, and more. The amplifier signals full in-play diagnostics including real-time load-current monitoring through I2S or I2C interfaces, enabling ASIL-A certification of safety-related applications like warning-tone generators and acoustic vehicle alerting systems (AVAS). A digital impedance meter is also provided, ensuring systems containing the TDA7901 can meet the most demanding requirements of automotive OEMs.

With its I2S digital input and intelligent quad-BTL output, the TDA7901 delivers 4 x 43W of audio power (at 4Ω load, saturated output at 14.4V). The amplifier has 80kHz bandwidth to handle high-definition audio. Its wide supply-voltage range, spanning 4.5V-18.5V, prevents disruption by start-stop engine operation and general automotive electrical transients.

The TDA7901 is due to enter production in the second half of 2022, in a Power-SO36 package.

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Lawrence has been covering engineering subjects – with a focus on motorsport technology – since 2007 and has edited and contributed to a variety of international titles. Currently, he is responsible for content across UKI Media & Events' portfolio of websites while also writing for the company's print titles.

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