ADAU1445 Analog Devices, ADAU1445 Datasheet - Page 18

• Manufacturer Part Number: ADAU1445
• Manufacturer: Analog Devices

Specifications of ADAU1445

• Instructions/cycles: 3584
• Digital I/o Channels: 24/24
• Analog I/o Channels: 0/0
• Product Description: Digital audio processor with flexible audio routing matrix, 8 × 2-channel ASRC

ADAU1442/ADAU1445/ADAU1446
OVERVIEW
The ADAU1442/ADAU1445/ADAU1446 are each a 24-channel
audio DSP with an integrated S/PDIF receiver and transmitter,
flexible serial audio ports, up to 16 channels of asynchronous
sample rate converters (ASRCs), flexible audio routing, and user
interface capabilities. Signal processing capabilities include
equalization, crossover, bass enhancement, multiband dynamics
processing, delay compensation, speaker compensation, and stereo
image widening. These algorithms can be used to compensate
for the real-world limitations of speakers, amplifiers, and listening
environments, resulting in an improvement in the perceived
audio quality.
An on-board oscillator can be connected to an external crystal to
generate the master clock. A phase-locked loop (PLL) allows the
ADAU1442/ADAU1445/ADAU1446 to be clocked from a variety
of clock frequencies. The PLL can accept inputs of 64 × f
256 × f
the core, where f
cessing mode. In dual- or quad-rate mode, these multipliers are
halved or quartered, respectively. System sample rates include, but
are not limited to, 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, and 192 kHz.
Each ADAU1442/ADAU1445/ADAU1446 operates from a 1.8 V
digital power supply and a 3.3 V analog supply. An on-board
voltage regulator can be used to operate the chip from a single
3.3 V supply.
The ADAU1442/ADAU1445/ADAU1446 have a sophisticated
control port that supports complete read and write capability of
all memory locations, excluding read-only addresses. Control
registers are provided to offer complete control of the chip’s
configuration and serial modes. Handshaking is included for
ease of memory uploads and downloads. The ADAU1442/
ADAU1445/ADAU1446 can be configured for either SPI or I
control. Program RAM, parameter RAM, and register contents can
be saved in an external EEPROM, from which the ADAU1442/
ADAU1445/ADAU1446 can self-boot on startup.
The ADAU1442/ADAU1445/ADAU1446 serial ports operate with
digital audio I/Os in the I
compatible mode. The flexible serial data ports allow for direct
interconnection to a variety of ADCs, DACs, and general-purpose
DSPs. The combination of an on-board S/PDIF transmitter and
receiver and 16 channels of ASRCs allows for easy compatibility
with an extensive number of external devices, and a system with
up to nine sampling rates.
The flexible audio routing matrix (FARM) is a system of multi-
plexers used to distribute the audio signals in the ADAU1442/
ADAU1445/ADAU1446 among the serial inputs and outputs,
audio core, and ASRCs. FARM can easily be configured by
setting the appropriate registers.
The ADAU1442, ADAU1445, and ADAU1446 are distinguished by
the number of on-board ASRCs and maximum sample rates. The
ADAU1442 contains eight 2-channel ASRCs, the ADAU1445
contains two 8-channel ASRCs, and the ADAU1446 has no ASRCs.
S
, 384 × f
S
, or 512 × f
S
is the sampling rate of audio in normal-rate pro-
2
S, left-justified, right-justified, or TDM-
S
to generate the internal master clock of
S
, 128 × f
2
C
Rev. C | Page 18 of 92
S
,
Two sets of serial ports at the input and output can operate in a
special flexible TDM mode, which allows the user to independently
assign byte-specific locations to audio streams at varying bit
depths. This mode ensures compatibility with codecs using
similar flexible TDM streams.
The core of the ADAU1442/ADAU1445/ADAU1446 is a 28-bit
DSP (or a 56-bit DSP when using double-precision mode)
optimized for audio processing, and it can process audio at
sample rates of up to 192 kHz. The program and parameter RAMs
can be loaded with a custom audio processing signal flow built
with the SigmaStudio graphical programming software from
Analog Devices, Inc. The values stored in the parameter RAM
control individual signal processing blocks, such as IIR and FIR
equalization filters, dynamics processors, audio delays, and mixer
levels. A software safeload feature allows for transparent
parameter updates and prevents clicks on the output signals.
Reliability features such as a CRC and program counter watchdog
help ensure that the system can detect and recover from any
errors related to memory corruption.
S/PDIF signals can be routed through an ASRC for processing
in the DSP or can be sent directly to output on MP pins for
recovery of the embedded audio signal. Other components of
the embedded signal, including status and user bits, are not lost
and can be output on the MP pins as well.
Multipurpose (MP) pins are available for providing a simple
user interface without the need for an external microcontroller.
Twelve pins are available to input external control signals and
output flags or controls to other devices in the system. Four of
these can alternatively be assigned to an auxiliary ADC for use
with analog controls such as potentiometers or system voltages.
As inputs, MP pins can be connected to push buttons, switches,
rotary encoders, potentiometers, or other external control circuitry
to control the internal signal processing program. When con-
figured as outputs, these pins can be used to drive LEDs (with a
buffer), to output flags to a microcontroller, to control other ICs,
or to connect to other external circuitry in an application.
The SigmaStudio software is used to program and control the
ADAU1442/ADAU1445/ADAU1446 through the control port.
Along with designing and tuning a signal flow, the software can
configure all of the DSP registers in real time and download a new
program and parameter into the external self-boot EEPROM.
SigmaStudio’s easy-to-use graphical interface allows anyone with
audio processing knowledge to easily design a DSP signal flow and
port it to a target application without the need for writing line-level
code. At the same time, the software provides enough flexibility
and programmability for an experienced DSP programmer to have
in-depth control of the design. In SigmaStudio, the user can add
signal processing cells from the library by dragging and dropping
cells, connect them together in a flow, compile the design, and load
the program and parameter files into the ADAU1442/ADAU1445/
ADAU1446 memory through the control port. The complicated
tasks of linking, compiling, and downloading the project are all
handled automatically by the software.