11 Advanced Features

From design simplicity to enhanced audio, advanced features can mean hardware or software related improvements. Analog-input power stages often require smaller circuits before the audio amplifier referred to as the pre-amp stage. Some device families such as the TPA322x offer selectable gains to simplify pre-amplifier circuitry. As mentioned before, almost all Class-D amplifiers require at least two supply-voltages to operate: the main supply voltage for amplifying the audio and a secondary rail for gates/logic. For systems that don’t already have an available secondary supply rail, adding one can be inconvenient and of course costly. A hardware feature addressing this is an integrated LDO to allow for single-supply operation, which the TPA322x family supports as well.

Digital-input devices with a DSP can offer even more advanced features. The integrated DSP can be used for equalization (EQ), dynamic range compression (DRC), automatic gain limiting (AGL), or even Class-H supply voltage envelope tracking. Perhaps one of the most impressive advanced features TI offers is PurePath™ Smart Amp technology. Using a PurePath Learning Board and a compatible smart amp such as TAS5825M, speakers can be characterized and tuned to increase loudness and improve frequency response without damaging a speaker. This A/B comparison experiment video shows the potential for improvement in a small voice recognition smart speaker. To learn more about advanced features in amplifiers, reference the TAS5825M Advanced Features application note.