Setting Up The Evaluation Boards; Power Supply; Digital Audio Inputs And Outputs; Analog Audio Inputs And Outputs - Analog Devices EVAL-AD1940EB Manual

EVAL-AD1940EB/AD1941EB

SETTING UP THE EVALUATION BOARDS

POWER SUPPLY

The AD1940EB/AD1941EB are powered by a single supply
through Coax Power Jack J14. The supply should be 9 V to 12 V
dc with the ability to source at least 700 mA. The connector's
polarity should be tip positive. This single supply is regulated to
separate 5 V analog and digital planes. The AD1940/AD1941
and AD1939 generate 2.5 V and 3.3 V, respectively, from the 5 V
supply using their on-board regulators.

DIGITAL AUDIO INPUTS AND OUTPUTS

Digital audio I/Os can be connected to the boards in two
different formats. First, the evaluation boards can input or
output a standard 2-channel S/PDIF stream. These I/Os can be
either electrical (Jack J1 and Jack J2) or optical (Fiber Optic
Modules U1 and U5). The input S/PDIF source is selected with
SW10. Both S/PDIF transmit streams are always on. The
S/PDIF I/O streams are connected to SDATA_IN0 and
SDATA_OUT0 and are active according to the specific switch
settings shown in Table 2 and Table 3.
Second, the digital audio I/O connections are in the 3-wire I
format. Input Header J11, Output Header J7, and Output
Header J8 can connect to external ADCs, DACs, and codecs
2
with an I S left-justified or right-justified data stream. Master
clock, left/right clock, and bit clock connections are also on
these headers. Up to four stereo audio streams can be input or
output on each of these headers. These audio streams, when
selected by the rotary mode switches, interface directly to the
serial data ports of the AD1940/AD1941. These headers also
serve as the I/Os for the multichannel TDM streams.

ANALOG AUDIO INPUTS AND OUTPUTS

The evaluation boards can input six analog audio signals and
can output eight signals. The converters connected to the
AD1940/AD1941 SigmaDSP are a 4 ADC/8 DAC AD1939 and
an AD1871 stereo ADC. The full-scale I/O voltage on these
connections is 1 V rms.
RCA Jack J18 to Jack J20 are the inputs to the ADCs.
RCA Jack J3 to Jack J6 and mini Jack J12, mini Jack J15, and
mini Jack J16 are the DAC output connectors. The output is
low-pass filtered with an anti-image filter and converted from a
differential voltage output to single-ended voltage by op-amps
U28 to U31. The filters' −3 dB cutoff frequency is 100 kHz and
has an approximate third order Bessel (linear phase) response.

CONTROL INTERFACE

PCB Connector J17 is the connection for the SPI and I
control signals. The AD1940EB/AD1941EB typically connect to
the SigmaStudio design tools with the EVAL-ADUSB1 USB
adapter board. This board connects to the PC's USB port and
2
S
outputs either SPI or I
AD1941EB. The USB adapter is provided with the evaluation
boards, or is available for standalone use in a target system. The
AD1940EB/AD1941EB can also connect directly to a PC's
parallel port through PCB Connector J17, although this isn't the
recommended control interface. The software connection is
further explained in the Evaluation Board Software section.
Rev. 0 | Page 4 of 32
2
C commands to the AD1940EB/
2
C