PCM1860: Getting only 16 bits of data on I2S

Hey Børge,

Thanks for bringing this to our attention. Allow me to look into this and give you a response within the next 24-48hrs. 

Ore.

Hello Børge,

Apologies for the late response. To better help you, please provide the mode selection(mode 0,1 or 2) you picked for this set up?  

Ore. 

Here you see the schematic I'm working on.

INT is floating. MD0..6 are connected to jumpers. See first thread for the jumper settings I'm testing with.

I use MD1=1, MD0=1 for 11: Master mode (256 × fS). I get the expected bit clock and LRCK (96kHz) out of the ADC with this setting.

Børge

Hey borge,

Thanks for clarifying. I would get back to you with more information regarding this issue.

Ore.

Hi Ore, 

have you been able to address this issue? 

Best regards, 

Børge

apologies for the delay, still debugging the issue to come up with results. You would soon receive an update about this issue.

Ore.  

Hello Børge, 

I was able to replicate your md0-6 set up and came around the same result of 16 bits/ch. 

Hello Borge, 

I just wanted to give you an update and let you know the issue is still being investigated. Please allow us some time to come up with a solution.

BR,

Ore.

Hi Ore, 

I'm glad you have replicated this and that you are investigating. Please keep me posted

Best regards, 

Børge

Hi Borge,

Our team is on holiday. Ore will get back to you by the end of the day Monday. Please do not reply to this message unless we have not answered you in a timely manner.

Thank you for your patience,
Jeff McPherson

Hello Borge, 

Expect a status update by next week. 

BR,

Ore

Hi Ore, 

Judging by the time this takes, I assume I have found a snag in the silicon. 

Which other part do you recommend that has similar specifications? The voltage range and input circuitry of the PCM1860 is great. I can use HW or I2C control. I2C is preferred. 

My team is getting closer to component selection for the next product generation. We must take the PCM1860/1861 off that list now.

Best regards,

Børge

Hi Ore, 

Does this mean that hte hardware controlled PCM1860 is locked to 16 data bits? 

Thanks,

Børge

Borge,

It would be incorrect to assume that without more proof. We're conducting some tests and getting close to being able to find out what the pcm1860 is fully capable of and why we get 16 bit data and how to get 24 bit data. 

You would get a status update by next week for sure. Thank you for being so patient.

BR, 

Ore.

Hello Borge, 

I tested the pcm1861 which is the other hardware controlled ADC in this series and we observed 24bits of data in the output. These were the test conditions: 

• 48kHz sample rate at 12.288MHz MCK (256fs mode):

• md1&md0=11, master mode 256fs; md3=0, fir filter; md6&5&2=110, ch1 differential input; md4=0,left-justified.
• Differential input signal at 4.2Vrms full-scale and then pushed to 6.3Vrms. I attached the 4.2Vrms result then the 6.3Vrms result. 

I also ran the software controlled pcm1864 to observe the data output and also got 24bits of data in its output.

• maintained the same sample rate and mck and used a single ended signal we observed at 2.1Vrms and pushed to 3.15Vrms.
• Adc in master mode; Left justified; md0&md1=00 for i2c control; md3-md6= floating; int= 0. 

It is a little odd we are getting the same 16bit of data I would run a couple more tests to see if the ADC can put out 24bits of data and give you an update by the end of the week. 

Regards,

Ore. 

Hello Borge, 

We were not able to get more than 16-bit out of the PCM1860, but any of the other ADCs in the PCM186x series including the ones mentioned in this thread would be a great alternative to get 24-bit data

I came across this thread on the same issue of not getting a 24-bit resolution: https://e2e.ti.com/support/audio-group/audio/f/audio-forum/545155/pcm1860-not-seeing-24-bit-resolution; the PCM1860 performance requires a 17 bits ENOB. 

If you need anymore support please let us know.

Regards,

Ore.