Texas Instruments TAS5708EVM, Руководство пользователя, Страница: 6 / 26

2.1.3 Loudspeaker Connectors
+
–
OUT B
OUT A
2.1.4 USB Interface
2.1.5 Digital Audio Interface SPDIF
2.1.6 ADC Interface
Installation
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CAUTION
All speaker outputs are biased at Vcc/2 and must not be connected to ground
(e.g., through an oscilloscope ground).
Loudspeaker connections vary by device setup. Consult the quick-start guide ( Section 4 ) for more details.
However, the following is a general guideline:
When connecting a speaker in BTL mode, connect the speaker’s two terminals (A&B or C&D) across two
outputs on the TAS5708(TAS5710)EVM.
Speakers or loads can be connected to the outputs A-D with clip leads, or cables can be made
with female connectors (JST VHR-2N) that can mate to male connectors on the EVM board.
Figure 5. BTL Connection
The TAS5708/10 registers are accessed through I
2
C™ bus lines SDA and SCL. The USB circuit and USB
connector on the MC57xxPSIA board facilitates the connection between a host computer and the device.
The EVM USB circuit is powered by the 5-V USB line of the host PC and is independent of the power
supplies available on the board. The USB device that is used is a TAS1020B from Texas Instruments.
The Digital Audio Interface SPDIF (RCA/OPTO) accepts digital audio data using the I
2
S protocol. See the
TAS5708/10 data sheet ( SLOS570 ) for more information.
The RCA connector and the OPTO connector are the two SPDIF interfaces on the MC57xxPSIA board.
The switch S3 toggles between the OPTO and RCA connector to accommodate the signal source. When
the RCA cable or optical cable is connected and the signal source is powered up, verify that the SPDIF
lock indicator (blue LED5) illuminates, confirming that a viable signal is available to the device. Install a
jumper on JP4 across the middle pin and the pin marked SPDIF to connect the digital source to SDIN1.
For detailed information on how the data and clocks are provided to the TAS5708/10, see the schematic
appearing at the end of this document and the DIR9001 device data sheet (
SLES198 ).
In the absence of a digital signal source, the PCM1808 ADC can be used to convert an analog audio
signal to a digital signal to the TAS5708/10. The DIR9001 still provides clock signals to the ADC in this
process. The DIR9001 oscillator frequency (Y2) determines the sampling frequency in the absence of a
digital signal. If the OSC frequency is 24 MHz, or if the OSC is set at 12 MHz, the sampling frequency
6 TAS5708(TAS5710)EVM SLOU232A – January 2009 – Revised January 2009
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