D2-7XX83 Datasheet, PDF (29/32 Pages) Intersil Corporation – Powered Speaker Systems

D2-7xx83
Audio Processing Functions
Each system design has its own firmware-dependent signal flow.
This signal flow may be generic, or specifically designed for a
particular amplifier application and consists of input elements
connected to various signal processing blocks, routing the audio
data to an output element. The input elements consist of chip
peripherals used for audio input (I²S input, S/PDIF Digital
receiver, and ADC). The output elements include the chip I²S
output, S/PDIF Digital transmitter, and PWM outputs.
Typical audio processing blocks include gain stages, mixers, tone
controls, compressors, limiters, equalizers, routers, loudness
contour, crossover filters, delays, as well as audio enhancement
features provided within the specific application firmware.
The input and output elements are configured by the firmware
application and the scope of I/O selection is generally specific to
the hardware of the particular application.
The signal processing blocks contain one or more parameters
that define the signal transfer characteristic of the block and a
mechanism for choosing the source and destination data
locations. The signal flow is created by connecting together the
signal processing blocks in the proper order to achieve the
overall system audio processing function.
Firmware Functions
D2-7xx83 IC contains a DSP supporting powerful audio
processing algorithms. Some of the standard audio algorithms
that are typically supported in all firmware loads. Other
algorithms are specific system design and firmware load
dependent.
Additional features support multiple system capabilities such as:
• Automatic power-on amplifier calibration
• Parameter control and status reporting
• Integrated power supply control and clock synchronization
• Automatic power supply high-voltage rail anti-pump control
• Automatic negative rail generation and bring-up control (for
select half-bridge designs where a ± rail is not already
supplied)
• Automatic cycle-by-cycle temperature sensing and system
response
• Automatic cycle-by-cycle current sensing and system response
• Input audio signal sensing and pop-free power-on/off via
D2Audio’s patented “Green Mode” algorithm with adjustable
threshold
• Dynamic adjustment of efficiency vs. distortion vs. output
power level via D2Audio’s patented “DynaTiming” algorithm
• AM radio interference avoidance mode allows for dynamic
switching of PWM engines when system microcontroller is in
AM Radio model
Input Source Selection
A source selection register specifies the action of a signal
multiplexer, which will implement a simple switching function.
The selected input will be routed to the block output unaltered.
All non-selected inputs will be ignored. Selections typically
include I²S inputs, S/PDIF Digital inputs, HD Audio inputs, and
ADC inputs.
Master Volume
A master volume function alters the level on all channels
simultaneously by applying the same gain/attenuation function
to each. A single parameter controls all channels.
Channel Attenuation
A channel attenuation function alters the level of a single
channel. A single parameter is provided for each channel.
Equalization
An equalization processing block consists of a single input and
output, and is characterized by how many frequency bands are
supported. Typical equalizers have 3-bands or 5-bands, although
multiple combinations are directly supported. Each frequency
band has 3 parameters - the center frequency, the filter Q, and
the filter gain.
Tone Control
Tone control provide simple bass and treble processing to the
audio signal. Each tone processing block includes two first-order
(6dB/octave) shelving filters, one each for bass and treble. Filters
include programmable corner frequency and gain settings.
Excursion Control
Excursion processing provides dynamic control of the subwoofer
response. Three audio processing control adjustments are
provided for frequency settings, and three adjustments are
provided for Q parameter settings.
Mixer
Mixer configuration blocks have multiple input channels and as
many output channels as required by the system implementation.
The mixer has an input gain parameter for each input to every
mixing node. (e.g. An 8-input mixer with 12 outputs incorporates a
total of 96 independent gain adjustment parameters.) The
minimum gain parameter value is infinite attenuation, or mute.
Mixers
An input mixer provides a two-input, two-output mixing and
routing path. All inputs can be mixed at adjustable gain into any
combination of outputs. Programmable settings are continuously
adjustable from unity (0 dB) gain, through full cut-off.
Compressor/Limiter
The compressor/limiter processor is used to gracefully limit the
dynamic range of the audio signal. This is useful to prevent the
amplifier from clipping or to limit the amplifier output power.
Each compressor/limiter has configurable Compression Ratio,
Threshold, Attack and Release Time, as well as Makeup Gain.
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FN7838.3
April 28, 2016