DEM-PCM1717
The
Figure 1 shows the block diagram of the DEM-PCM1717. The user must supply 4 digital audio signals, power, and mode control signals. The DAC will then provide two channels of either directly or capacitively coupled analog outputs.
The PCM1717 can be operated either in a hardware or software mode. In the software mode either external logic or a processor is used to program four registers internal to the PCM1717. (Consult the data sheet for additional informa- tion).
The hardware mode can be evaluated using this fixture by use of the on board DIP switches. These switches are connected to pins on the PCM1717 which force either power or ground to the pin. In the hardware mode some of the features of the PCM1717 can be exercised. The selection between the hardware and software mode is done using the mode switch on the
CN1
CLKO
XTI
BCK
LRCK
DIN
GND
S1
5
PCM1717E
ML MC MD RSTB GND +VCC
CN2
4
CN3
VOL • C
VOL • D
VOR • D
VOR • C
ZO
GND
R1
+VCC
FIGURE 1. DEM-PCM1717 Block Diagram.
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Low |
| Mute |
| Off |
| Off |
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| Reset |
| Hardware |
| On |
| On |
| 48kHz |
| 44.1kHz |
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| Off |
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High |
| Mute |
| 44.1kHz |
| 48kHz |
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| Reset |
| Software |
| Off |
| Off |
| 32kHz |
| 32kHz |
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| On |
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| ML |
| MC |
| MD | RSTB |
| Mode |
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FIGURE 2. DEM-PCM1717 Switch Settings.
HARDWARE DESCRIPTION
Figure 3 shows the schematic diagram of the DEM-PCM1717 evaluation board.
Figure 4 illustrates the PC board design and component placement for the DEM-PCM1717 evaluation board. Note on the parts layout that there are 3 connectors CN1, CN2, and CN3. CN1 is used to connect the digital audio signals to the PCM1717. CN2 is used connect the control lines for the PCM1717 as well as power and ground. CN3 is used to access the audio output from the PCM1717. The analog outputs are available as DC-coupled (VOR-D, VOL-D) or ac-coupled (VOR-C, VOL-C). The DC coupled output is referred to ground, and the AC- coupled output is referred to VCC/2, typically 2.5V. There is also a connection for the output of the zero detect flag. Use of this pin requires a pull- up resistor, R1. This resistor is labeled R1 on the schematic and the board and a typical value is 4.7kΩ.
The crystal (U1) is not included.
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