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DIT4096/DIT4192

PD Di Giacomo
Prodigy 30 points
Other Parts Discussed in Thread: DIT4096

We are having a problem with either of these 2 SPDIF TX chips. If the COPY and GENERATION (L) bits are set to "Pro", some Crystal RX chips read the wrong TX frequency. If the bits are set to any of the "Consumer" modes, the old Yamaha RX chip read the wrong frequency info.

Yes, aside from the fact the frequency read-out is wrong, they work. But, some of our customer's units need that frequency info, in order to switch in the right VCXO. (Yes, most don't have a secondary VCXO. It might only be 1% or so, but this problem has to be solved.)

Not that it matters, but I am sure someone will ask:

System clock is 11.2896 MHz. L/R clock is (obviously) 44.1 kHz. Operating in h/w mode. And, yes, the validity bit is set right, or none of our customers units would work.

Anyone want to guess what is wrong?

 

 

 

 

 

  • 0
    TI__Intellectual 2810 points

    Hello,

    If you are using the DIT4096/4192 in Hardware mode with the CSS pin forced low, then the device will operate in a very limited mode where the sampling frequency bits in the channel status data will indicate a fixed 48kHz. There is no mechanism in the DIT4096/4192 to detect the SYNC clock rate and set the sampling frequency bits automatically.

    In order to have full control over the channel status data, you will need to operate the device in Hardware Mode with CSS forced high, or in Software mode using an SPI host. The data sheet includes details for both scenarios.



    Regards,

    Bob Martin, Systems Engineering - TI Audio Converters

  • 0 in reply to Bob Martin
    Prodigy 30 points

    OK, I am ordering a boatload of the Crystal equivalent. Would be nice if this was in the App note.

     

    Probably the last time I buy a TI chip. Just another example of great engineering. Just like the DIR170x series.

    Thanks for your prompt reply. It is appreciated.

     

  • 0 in reply to PD Di Giacomo
    Prodigy 30 points

    OK, follow-up, just in case anyone cares.

     

    A digit-widget buddy, that used to owe me a favor, had a good idea. Set CSS=1, and C=0. Forces all Channel Status bits to be "0". Which, turns out to be Consumer Mode, 44 kHz, no de-emp. and 1st generation, with copy protect enabled.

    That works. Good enough to use up our inventory of DIT4096 chips. (We bought a lot, as they were getting scarce, at one time. Gotta do something with them.)

    Now I owe my digit-widget buddy a favor.