EVAL-AD1954EB Analog Devices Inc, EVAL-AD1954EB Datasheet - Page 9

• Manufacturer Part Number: EVAL-AD1954EB
• Description: BOARD EVAL FOR AD1954
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD1954EB

• Rohs Status: RoHS non-compliant

GENERAL DESCRIPTION (continued from page 1)
An extensive SPI port allows click-free parameter updates, along
with read-back capability from any point in the algorithm flow.
The AD1954 includes ADI’s patented multibit - DAC architec-
ture.This architecture provides 112 dB SNR and dynamic range
and THD+N of –100 dB. These specifications allow the AD1954
to be used in applications ranging from low-end boom boxes to
high-end professional mixing/editing systems.
The AD1954 also has a digital output that allows it to be used
purely as a DSP. This digital output can also be used to drive an
external DAC to extend the number of channels beyond the three
that are provided on the chip.
This chip can be used with either its default signal processing
program or with a custom user-designed program. Graphical pro-
gramming tools are available from ADI for custom programming.
FEATURES
The AD1954 is comprised of a 26-bit DSP (48 bits with double
precision) for interpolation and audio processing, three multibit
- modulators, and analog output drive circuitry. Other features
include an on-chip parameter RAM that uses a safe-upload feature
for transparent and simultaneous updates of filter coefficients and
digital de-emphasis filters. Also, on-chip input selectors allow up
to three sources of serial data and master clock to be selected.
The 3-channel configuration is especially useful for 2.1 playback
systems that include two satellite speakers and a subwoofer.
The default program allows for independent equalization and
compression/limiting for the satellite and subwoofer outputs.
Figure 1 shows the block diagram of the device.
REV. A
SERIAL DATA I/O
AUX SERIAL
DATA INPUT
CLOCK I/O
MASTER
GROUP
GROUP
GROUP
SPI I/O
3
3
3
3
3
NOTES
1
2
CONTROLLED THROUGH SPI CONTROL REGISTERS.
DAC DOES NOT USE DIGITAL INTERPOLATION.
AUDIO
MCLK
MUX
MUX
FILTCAP
DATA
SPI PORT
3:1
3:1
DVDD
1
1
AVDD
256
(256
3
GENERATOR
REGISTERS
REGISTERS
TRAP REG.
SAFELOAD
CONTROL
f
(I
S
f
2
MCLK
S
/512
S, SPI)
ZEROFLAG
Figure 1. Block Diagram
/512
SERIAL
IN
f
S
f
1
S
OUT
IN)
1
ODVDD
–9–
3.45 (DOUBLE PRECISION)
3.23 (SINGLE PRECISION)
The AD1954 contains a program RAM that boots from an internal
program ROM on power-up. Signal processing parameters are
stored in a 256-location parameter RAM, which is initialized on
power-up by an internal boot ROM. New values are written to
the parameter RAM using the SPI port. The values stored in the
parameter RAM control the IIR equalization filters, the dual-
band compressor/limiter, the delay values, and the settings of the
stereo spreading algorithm.
The AD1954 has a very sophisticated SPI port that supports
complete read/write capability of both the program and the para-
meter RAM. Two control registers are also provided to control
the chip serial modes and various other optional features. Hand-
shaking is also included for ease of memory uploads/downloads.
The AD1954 contains four independent data capture circuits,
which can be programmed to tap the signal flow of the processor
at any point in the DSP algorithm flow. These captured signals
can be accessed either through a separate serial out pin (i.e., that
can be connected to an external DAC or DSP) or by reading from
the data capture SPI registers. This allows the basic functionality
of the AD1954 to be easily extended.
The processor core in the AD1954 has been designed from the
ground up for straightforward coding of sophisticated compres-
sion/limiting algorithms. The AD1954 contains two independent
compressor/limiters with rms based amplitude detection and
attack/hold/release controls, together with an arbitrary compression
curve that is loaded by the user into a look-up table that resides
in the parameter RAM. The compressor also features look-ahead
compression that prevents compressor overshoots.
PROGRAM
MEMORY CONTROLLERS
512  35
DATA MEMORY, 512  26
RAM
DATA FORMAT:
DSP CORE
26  22
PARAMETER
256  22
RESETB
RAM
AGND
3
VREF
MUTE DE-EMPHASIS
REFERENCE
DAC – SW
DCSOUT TRAP
DGND
VOLTAGE
DAC – L
DAC – R
COEFFICIENT
BIAS
64  22
ROM
2
2
DCSOUT
ANALOG
BIAS GROUP
ANALOG
OUTPUTS
AD1954