Class-D digital PAs for a better in-car audio experience

December 22, 2015 // By Graham Prophet
ST’s latest audio power Amplifiers for car audio deliver cleaner sound and simplify system design; ST says that these second-generation digital audio amplifiers bring increased performance, with new components that simplify system design and lower cost for car-radio suppliers while delivering clearer sound to drivers and passengers

ST’s second-generation FDA801 and FDA801B 4-channel class-D amplifiers with digital input convert the digital audio source directly into high-quality sound. The digital input gives immunity to GSM noise, improves sound quality, saves component costs, and simplifies system design. ST introduced the first class-D digital-input automotive-audio amplifiers in 2012, and is now moving forward with its new and improved second generation that will be soon completed with pin-compatible ICs in various multi-channel configurations.

“Class-D amplifiers are revolutionising in-car audio throughout the marketplace, from audiophile systems in prestige vehicles to affordable, high-quality sound in smaller cars,” said Alfio Russo, Group VP, General Manager Audio & Body Division, Automotive Product Group, STMicroelectronics.

These power amplifiers combine superior audio quality and increased energy efficiency, as well as the unique real-time measurement of speaker impedance via the new Digital Impedance Meter (FDA801B), which represents a step forward, ST asserts, in automotive diagnostics compared to any other audio amplifier.

Like their predecessors, ST’s new amplifiers are compatible with fuel-saving start-stop technology, maintaining uninterrupted playback when the vehicle battery voltage dips as the engine is restarted. The FDA801 and FDA801B are available, in “ high volumes only” in a LQFP64 Exposed Pad Up package that allows efficient heatsink attachment.

Features include;

  1. 115 dB Signal to Noise Ratio (SNR); 110 dB dynamic range;
  2. Simplified digital input eliminates external DAC and external decoupling capacitor, thereby avoiding potential DC-offset problems;
  3. More than 40% power saving compared to standard class-D amplifiers;
  4. Digital Impedance Meter (DIM, in FDA801B) automatically recognises magnitude and phase of the connected speaker and communicates it by digital bus (I²C);
  5. Internal 24-bit DAC conversion and very low noise in line-driver and amplifier modes ensure superior audio performance;
  6. On-demand advanced diagnostics allows each channel to independently perform AC or DC diagnostics with configurable parameters;
  7. Ability to drive loads down to 1 ohm gives designers complete flexibility to specify preferred speakers.