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SN74LVC125A: I2S buffer IC

Stephan P
Prodigy 220 points
Part Number: SN74LVC125A
Other Parts Discussed in Thread: SN74CBTLV3257, SN74LVC3G34, TMUX1574

Hi TI forum,

I'm looking for a suitable I2S buffer IC for an audio application. In the application digital audio needs to be routed from a selectable audio source to 8 identical subsystems as shown in the block diagram below. The system will be implemented on a single PCB.

I am considering to use SN74LVC125A ICs for the buffers since they are 4channel devices. The I2S signals are MCLK (36.864MHz), BCLK (12.288MHz), FCLK (192kHz) and SDATA, the signal level is 3.3V.

Here my questions:

1) Is the SN74LVC125A a suitable device for this application or do you recommend a different IC?

2) Would one SN74LVC125A IC be capable of driving the 8 subsystems alone or will I need two layers of buffers as shown in the block diagram? 

3) Do you see any issues with using the SN74CBTLV3257 as I2S demultiplexer in this application?

Thanks a lot,

Stephan

  • 0
    Guru 252780 points

    1. At 3.3 V, LVC family devices have the strongest outputs, and are best suited as buffers.

    2. 24 inputs are a higher load than 8 inputs. How much larger the load is depends also on the trace length, so my answer is a definitive "maybe". Using SN74LVC3G34 to buffer only the three clock signals would save space.

    3. The TMUX1574 has better electrical characteristics for the same price.