ADAU1761 jack detect with capless headphone
Hi I'm working on a project with the ADAU1761. I have my schematic setup for capless headphone output, but I'd also like to use the jack detect feature. There isn't much information on jack detection in the datasheet and a google search just gives me an app note on protecting the output from a DC line output. Could you give me an example of how to hook up the jack detect in capless mode?
Also on my LAUX, RAUX line input I want to bring in a line input from a phone or mp3 player. The datasheet shows a 1K serial resistor with an ac coupling cap. However the eval board has a 49.9k resistor to gnd as well after the 1K. I wasn't sure what the purpose of that was and if I needed it.
I've attached the schematic I have so far.
Thank you,
-Eric
This question has been closed by the EZ team and is assumed answered.
Hello Eric,
Sorry I missed this question earlier. I just saw it while searching for something else.
Regarding the 49K9 resistor. It is there to bleed off any DC that might build up from either an external device or from leakage in the electrolytic coupling caps. The leakage would cause the signal at the jack to have some DC on it when nothing is plugged in. Then when you plug it in you would get a pop. The resistor serves to keep the DC voltage from building up.
Regarding the jack detect. It was not correctly implemented in this part so it is not useful.
Here is a post that explains it.
(+) jack detection with ADAU1361 - Q&A - SigmaDSP Processors & SigmaStudio Dev. Tool - EngineerZone (analog.com)
The solution is to connect the switch in the jack to either a system controller or to a GPIO pin on the DSP.
Dave T
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