Texas Instruments DEM-DAI3793A manual Master Mode with Audio Precision SYS-2722

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Master Mode with Audio Precision SYS-2722

5.2Master Mode with Audio Precision SYS-2722

To enable the DEM-DAI3793A/3794A EVM motherboard for use in Master mode, the path of the S/PDIF input to the PCM3793A through DIR is not available for use. LRCK and BCK change the respective output states at the PCM3793A side in master mode; the respective jumpers of R-BCK, R-LRCK, and RX-DATA should be removed from CN305 to avoid conflict between the input and output of these clocks.

Furthermore, in this situation, DIN to the PCM3793A is also invalid because DIR LC89052T does not receive clocks (LC89052T cannot work in slave mode). Therefore, any analog output from the DAC is invalid because there is no data input.

However, in this configuration, users can confirm master mode operation of both LRCK and BCK from PCM3793A with a digital oscilloscope. Users can easily identify master mode without the use of other external equipment such as the PSIA-2722 analyzer.

The PCM3793A has no integrated internal PLL. However, the clock manager function can provide LRCK (fS) and BCK in master mode, as described in Figure 5-3.

U302

CN302

U301

CN301

		SCKI	Clock
			Manager
SW001	DIR:LC89052T￿	BCK	ADC	DAC
		DIN	AudioInterface￿
		LRCK
SW301	DIT:￿DIT4096	DOUT
				PCM3793A
Daughter￿card￿#2			Daughter￿card￿#1
			Isolated￿by
			CN305

Figure 5-3. Master Mode Configuration With SYS-2722

Refer to the jumper combination shown in Figure 5-4to put the DEM-DAI3793A/3794A EVM motherboard into master mode configuration.

52 Evaluation and Measurements SBAU127 –July 2007

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