TFA9890UK: Boosted class-D audio amplifier with speaker boost protection algorithm ARCHIVED

The TFA9890 is a high efficiency class-D audio amplifier with a sophisticated speaker boost and protection algorithm. It can deliver 7.2 W peak output power into an 8 Ω speaker at a supply voltage of 3.6 V. The internal boost converter raises the supply voltage to 9.5 V, providing ample headroom for major improvements in sound quality.

A safe working environment is provided for the speaker under all operating conditions. The TFA9890 maximizes acoustic output while ensuring diaphragm displacement and voice coil temperature do not exceed their rated limits. This function is based on a speaker box model that operates in all loudspeaker environments (e.g. free air, closed box or vented box). Furthermore, advanced signal processing ensures the quality of the audio signal is never degraded by unwanted clipping or distortion in the amplifier or speaker.

Unlike competing solutions, the adaptive sound maximizer algorithm uses feedback to accurately calculate both the temperature and the excursion, allowing the TFA9890 to adapt to changes in the acoustic environment.

Internal intelligent DC-to-DC conversion boosts the supply rail to provide additional headroom and power output. The supply voltage is only raised when necessary. This maximizes the output power of the class-D audio amplifier while limiting quiescent power consumption.

The TFA9890 also incorporates advanced battery protection. By limiting the supply current when the battery voltage is low, it prevents the audio system from drawing excessive load currents from the battery, which could cause a system undervoltage. The advanced processor minimizes the impact of a falling battery voltage on the audio quality by preventing distortion as the battery discharges.

The device features low RF susceptibility because it has a digital input interface that is insensitive to clock jitter. The second order closed loop architecture used in a class-D audio amplifier provides excellent audio performance and high supply voltage ripple rejection. The audio input interface is I²S and the control settings are communicated via an I²C-bus interface.

The device also provides the speaker with robust protection against ESD damage. In a typical application, no additional components are needed to withstand a 15 kV discharge on the speaker.

The TFA9890 is available in a 49-bump WLCSP (Wafer Level Chip-Size Package) with a 400 μm pitch.