Have a Problem with PCM1808 - Page 1
Forum section: electronics / projects

author: cereyan_mühendisi
author_rank: Newbie
timestamp: June 14, 2016, 11:24:25 pm
content: Hi guys, this is my first post in the forum. And it will be a question.Thank you in advance whoever answer my question and Dave for this forum and videos.I want to describe my circuit shortly:I used PCM1808 24-bit, 96kHz Audio ADC in my project. And I used PLL1705 as clock source for it which is recomended in the datasheet of PCM1808. The PCM1808 is in master mode to feed another digital audio ic which is not important at the moment.And my problem is that I can see the proper clocks at the output pins of the PCM1808, like BCK and LRCK but I can not see any proper data signal at the DOUT pin. What do you think the reason is for that situation? My only guess is that maybe I damaged that particular pin while soldering. But I am not sure if it is the real problem and if it is possible to damage just one pin.But I am going to replace it with another PCM1808 asap. When I do that I will inform you about the result.And I have some oscilloscope pictures to show you:This is LRCK signal which has lowest freq:And this is BCK:AND DATA OUT which is absent:And this is extra: the master clock (24,576 MHz) from PLL1705 to PCM1808 and other ic. I have a small question too about the shape of that clock. Is it normal?Thanks,Emre

author: Buriedcode
author_rank: Super Contributor
timestamp: June 15, 2016, 10:47:53 am
content: Waveforms look fine, but I would buffer the output of the PLL for the ADC, at that frequency impedances on prototypes can play havoc with edges. Also the ADC will only output 'data' after the power on sequence, and with a stable clock, have to checked both power connections to the ADC? Pages 12 and 13 of the datasheet shows the power on sequence.Obviously without an input waveform most of the MSB's of the data will be 0.I had this chip running on....veroboard... and even on that, with proper decoupling, seemed to work rather well. I had to use a tinylogic buffer for the system clock though, probably because of the less-than-ideal setup. Even without it I got *some* data, but it kept resetting.

author: cereyan_mühendisi
author_rank: Newbie
timestamp: June 15, 2016, 10:28:06 pm
content: Hi Buriedcode, thanks for the reply.I resolved the problem. As I said I replaced it and circuit worked well. My project is about visible light communicating.And this is the video of my project:https://youtu.be/lB8voFO3h44

author: alexmaurer
author_rank: Newbie
timestamp: November 18, 2022, 09:47:04 am
content: Exactly the same behavior here today !!!On a test board. No output on DOUT.DOUT was connected to nothing...I saw your post, changed the IC and DOUT is working.What the

author: tom_91p
author_rank: Newbie
timestamp: July 28, 2025, 03:54:48 pm
content: Hello there,I have the same sort of problem, but I am using my ESP32-S3 as a master clock source.I've checked all input signals, they look the same as the ones on the picture.And unfortunately, I have only little noise on the DOUT pin...I am sure that the PCM1808 recieves well the signals.I've seen on the PCM1808 manufacturer datasheet that the problem might be the clock source that doesn't generate perfectly aligned clock signals. Therefore, the PCM1808 mute automatically the output.What do you all think I can do to solve my output signal problem ?