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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
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.