EVAL-AD1940EB/AD1941EB
Rev. 0 | Page 7 of 32
IC FUNCTIONS
Table 4 explains the function of each IC on the evaluation
boards. The two large Lattice CPLDs (U13 and U15) are used
only for routing signals on the board and do not perform
decoding or signal conditioning.
Table 4. IC Functions
Reference
Designator
Function
U1
AD1940/AD1941 SigmaDSP audio processor
U10
AD1939 4 ADC/8 DAC audio codec
U9
AD1871 stereo ADC
U13, U15
Lattice M4A5-128/64 CPLDs for signal routing
U14,
U17 to U20,
U26 to U31
AD8606 dual op amps for analog audio I/O
buffering
U11
ADP3303-5 LDO Regulator, 5.0 V analog supply
U8
LM317AT, 5.0 V digital supply
U12
ADM811 reset generator
U32, U33
74HC125 for external MCLK I/O buffering
U3
74HC04 for driving LEDs
U22
74HC541 for buffering SPI signals
U2
CS8414 S/PDIF receiver
U4
CS8404 S/PDIF transmitter
LED FUNCTIONS
The four LEDs on the evaluation boards are useful components
that indicate the boards are properly powered and set up. Table
5 explains what each LED indicates.
Table 5. LED Functions
Reference
Designator
Function
D1
When lit, U2 is receiving no data, or an invalid
S/PDIF stream.
When dim, U2 is receiving valid S/PDIF data.
D2
When lit, the SPI or I
2
C connection is inactive.
When dim, an SPI or I
2
C connection has been
established.
When blinking, an SPI or I
2
C transaction is
occurring.
D6
Ind5 V DV
DD
D11
Ind5 V AV
DD
RESET
The AD1940EB/1941EB can be reset with push-button switch
SW1. This reset signal is debounced by the ADM811 (U12).
This reset signal affects the AD1940/AD1941, AD1939,
AD1871, and S/PDIF receiver and transmitter. The boards can
also be reset by disconnecting the power. After reset, the
AD1940EB/AD1941
EB
do not pass audio and a control port write
has to be performed so that signals are output again. See the
Using SigmaStudio section for additional information.
AD1940EB/AD1941EB DIFFERENCES
The main difference between the AD1940EB and AD1941EB is
the control port. The AD1940EB uses an SPI control port,
whereas the AD1941EB uses an I
2
C port. The same PCB is used
for both assemblies, with slight modifications. To accommodate
for I
2
C communication, the AD1941EB’s CPLDs have slightly
different programs than those of the AD1940EB. Also, the
AD1941EB has Resistor R56, Resistor R57, Resistor R72, and
Resistor R73, while the AD1940EB does not.
Summary of Contents for EVAL-AD1940EB
Page 12: ...EVAL AD1940EB AD1941EB Rev 0 Page 12 of 32 05880 003 Figure 3 AD1939 Analog Input Filters...
Page 13: ...EVAL AD1940EB AD1941EB Rev 0 Page 13 of 32 05880 004 Figure 4 AD1871 Analog Input...
Page 15: ...EVAL AD1940EB AD1941EB Rev 0 Page 15 of 32 05880 006 Figure 6 Input CPLD...
Page 16: ...EVAL AD1940EB AD1941EB Rev 0 Page 16 of 32 05880 007 Figure 7 AD1940 AD1941 SigmaDSP...
Page 17: ...EVAL AD1940EB AD1941EB Rev 0 Page 17 of 32 05880 008 Figure 8 Output CPLD...
Page 20: ...EVAL AD1940EB AD1941EB Rev 0 Page 20 of 32 05880 011 Figure 11 AD1939 Codec...
Page 21: ...EVAL AD1940EB AD1941EB Rev 0 Page 21 of 32 05880 012 Figure 12 External Digital Outputs...
Page 22: ...EVAL AD1940EB AD1941EB Rev 0 Page 22 of 32 05880 013 Figure 13 SPI I2 C Control Interface...
Page 23: ...EVAL AD1940EB AD1941EB Rev 0 Page 23 of 32 05880 014 Figure 14 Power Supply...
Page 30: ...EVAL AD1940EB AD1941EB Rev 0 Page 30 of 32 NOTES...
Page 31: ...EVAL AD1940EB AD1941EB Rev 0 Page 31 of 32 NOTES...
