Automotive audio amplifier combines HD sound with class-G efficiency

In class-G operation, the TDA7901 buck controller automatically optimises the voltage supplied to the bridge-tied load (BTL) power stage depending on the audio signal level. STMicroelectronics’ TDA7901 automotive amplifier integrates a buck controller for class-G power switching and supports high definition (HD) audio for audio and efficiency performance.

According to STMicroelectronics, the smooth, analogue sound comes with near-class-D efficiency at normal listening levels. Power dissipation is much lower compared with a conventional class-A/B amplifier, says STMicroelectronics. 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, advises ST.

The TDA7901 can be used in many in-vehicle information (IVI) systems, such as head units, smart cockpit systems and external amplifiers. 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 ensures systems containing the TDA7901 can meet automotive OEM requirements, adds the company.

The controller has an I2S digital input and intelligent quad-BTL output to deliver four 43W of audio power (at 4 Ohm load, saturated output at 14.4V). The amplifier has 80kHz bandwidth to handle HD audio. The wide supply voltage range of 4.5 to 18.5V is claimed to prevent 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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