Class D audio amplifier targets safety applications

Class D audio amplifier targets safety applications

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With the HFDA801A, STMicroelectronics offers a high-resolution audio amplifier specifically designed for compact and cost-effective automotive applications. In view of its use in safety-relevant applications such as Acoustic Vehicle Alerting Systems, the device is equipped with appropriate diagnostic functions.
By Christoph Hammerschmidt


The HFDA801A is a 2 MHz switching class D amplifier with PWM (pulse width modulation) and quad bridge configuration. The integrated, high-performance D/A converter (DAC) guarantees hi-fi sound quality under any load conditions, combined with noiseless switching on and off without output artefacts. With a signal-to-noise ratio of 121 dB, a dynamic range of 120 dB and an output noise of only 10 µV, the cost-effective and compact HFDA801A achieves an exceptional level of audio performance.

The negative feedback configuration with integrated LC low-pass filter provides an extremely wide, flat frequency response up to 80 kHz and minimises dependence on external components. The wide bandwidth enables use in high definition (HD) audio applications, where designers can benefit from the device’s excellent linearity and low distortion, which is also independent of the quality of the inductors and capacitors.

The special architecture implemented in the HFDA801A derives all the required voltages internally, allowing the device to be powered from the vehicle’s electrical system without the need for additional power converters. The amplifier also benefits from its wide load range and can provide stable performance even when delivering high power on all four channels to loads with an impedance as low as 2 ohms.

Furthermore, thanks to an integrated in-play diagnostics, a digital impedance meter and a real-time load current monitor, the HFDA801A can be used in safety-relevant audio applications for which ASIL compliance must be demonstrated. An example of this is AVAS (Acoustic Vehicle Alerting System) systems.

The HFDA801A is currently sampling and will enter mass production in the second half of 2021.

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