TFA9888_SDS All information provided in this document is subject to legal disclaimers. © NXP B.V. 2017. All rights reserved.
Product short data sheet Rev. 2 — 14 July 2017 6 of 16
NXP Semiconductors
TFA9888
9.7 V stereo boosted audio system with adaptive sound maximizer and
speaker protection
8. Functional description
The TFA9888 is a highly efficient stereo Bridge Tied Load (BTL) class-D audio amplifier
with a sophisticated speaker-boost and protection algorithm. Figure 1
is a block diagram
of the TFA9888.
It contains a TDM/I
2
S input/output interface for communicating with the audio host. The
TDM/I
2
S data pins (DIO1, DIO2 and GAINIO) can be configured as inputs or outputs. It is
possible to configure the interface in full duplex mode with one data pin. Some TDM slots
can be configured as data inputs and others as TDM data outputs per TDM frame sync.
The maximum number of slots is 16 and the minimum number is 2 (like I
2
S). The interface
is therefore compliant with all I
2
S interface configurations and supports a wide range of
TDM interface configurations.
A PDM input stream can be applied to the TFA9888 (via pin PDMI). This audio interface
can be used for connecting digital microphones or connected to the audio host.
A speaker-boost and protection algorithm, running on a CoolFlux Digital Signal Processor
(DSP) core, maximizes the acoustical output of the speaker while limiting membrane
excursion and voice coil temperature to a safe level. The mechanical protection
implemented guarantees that speaker membrane excursion never exceeds its rated limit,
to an accuracy of 10 %. Thermal protection guarantees that the voice coil temperature
never exceeds its rated limit, to an accuracy of 10 C. Furthermore, advanced signal
processing ensures the audio quality is always acceptable.
The speaker-boost and protection algorithm implements an adaptive loudspeaker model
that is used to predict the extent of membrane excursion. The model is continuously
updated to ensure that the protection scheme remains effective even when speaker
parameter values change or the acoustic enclosure is modified.
Transparent top view
Fig 3. Bump mapping
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