Boosted class-D audio amplifier with SpeakerBoost protection algorithm and dynamic range compressor TFA9895_SDS0 pages

TFA9895
Boosted class-D audio amplifier with speaker boost
protection and multiband dynamic range compressor
Rev. 1 — 23 October 2013

Product short data sheet

1. General description
The TFA9895 is a high efficiency class-D audio amplifier with a sophisticated speaker
boost protection algorithm that features multi-band compression. It can deliver 2.65 W
(RMS; THD = 1 %) output power into a 4 speaker at a battery voltage of 3.6 V. The
internal boost converter raises the supply voltage to 5.3 V, providing ample headroom for
major improvements in sound quality.
A safe working environment is provided for the speaker under all operating conditions.
The TFA9895 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 that 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 TFA9895 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
precaution maximizes the output power of the class-D audio amplifier while limiting
quiescent power consumption.
The multi-band processing improves audio quality and apparent volume by allowing the
gain to remain stable in most of the signal while the protection reacts to only those
portions that would be unsafe. The TFA9895 also adds a high-frequency noise gate that
improves the sound of poor-quality audio sources.
The TFA9895 also incorporates advanced battery protection. By limiting the supply
current when the battery voltage is low, it prevents the audio system 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 TFA9895 is available in a 29-bump WLCSP (Wafer Level Chip-Size Package) with a
400 m pitch.