topic Re: iMX53 and SPDIF input in i.MX Processors

iMX53 and SPDIF input

AndrejBarbis — Fri, 19 Oct 2012 05:30:55 GMT

Hi,

can anybody know, what kind of input is SPDIF_Rx pin? Do i need to transform tipical SPDIF signal to TLL logic [3.3V] or is it this transformation done in processor?

Thank you

Regards

Andrej Barbis

Re: iMX53 and SPDIF input

Yuri — Wed, 24 Oct 2012 08:36:19 GMT

The (input) signals should be transformed to voltage level NVCC_GPIO.
There are three working points for NVCC_GPIO : 1.8V ; 2.775V ; 3.3V.

High-Level DC input voltage,VIH should be in range 0.7V x NVCC_GPIO - NVCC_GPIO.

Low-Level DC input voltage, VIL should be in range 0V - 0.3 x NVCC_GPIO.

Re: iMX53 and SPDIF input

haku_sato — Fri, 26 Oct 2012 12:46:54 GMT

Hi Andrej and Yuri,

One thing to be care ful of. SPDIF or IEC60958 signal is 0.5 to 0.6V Pk-pk. So, yes you have to convert the signal level of your choice to match what Yuri mentioned. One other thing to be really careful is to make sure that the edge rate and propagation delay for rise/fall time must be kept or you will end up with severe jitter degrading the signal quality. So, make sure to use high speed level shifter with close rise/fall time spec.

Also, depending on whether Coax (75ohm) or Optical connection could change the signal level, too. So you may have to factor that in.

Take care.

Haku