BTL Power Stage Supply Voltage Automatic Optimization
Lower power loss compared to conventional Class A/B amplifiers

STMicroelectronics (ST) has launched an integrated automotive audio amplifier that combines high sound quality and Class-G efficiency.

On the 14th, ST released the TDA7901 automotive audio amplifier, which integrates a buck controller for Class-G power switching and supports high-quality audio combining excellent sound quality and high efficiency.

The TDA7901 buck controller automatically optimizes the voltage supplied to the Bridge-Tied Load (BTL) power stage according to the audio signal level for Class-G operation, providing smooth analog sound with efficiency close to Class-D at normal listening levels.

Because power loss is much lower compared to conventional Class A/B amplifiers, heatsink requirements can be optimized, and system size and weight can be reduced by integrating the buck controller into the IC. Additionally, the Bill of Materials (BoM) can be reduced, circuit design can be simplified, and the burden of developing firmware that controls voltage rails can be reduced.

The TDA7901 is suitable for various in-vehicle information systems such as head units, smart cockpit systems, and external amplifiers. This amplifier achieves ASIL-A certification for safety-related applications, such as warning beep generators and Acoustic Vehicle Alerting Systems (AVAS), while transmitting overall operational diagnostic signals, including real-time load current monitoring, via I2S or I2C interfaces. Since a digital impedance meter is also provided, systems incorporating the TDA7901 can meet even the most stringent requirements of automotive OEMs.

Equipped with I2S digital inputs and intelligent quad BTL outputs, the TDA7901 provides 4x 43W audio output (saturated output at 14.4V with a 4Ω load). This amplifier features an 80kHz bandwidth capable of handling high-quality audio. The wide supply voltage range of 4.5V to 18.5V prevents malfunctions caused by common automotive electrical transients, including engine shutdowns during start/stop.