This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hi,
I've built a serval of the remote volume module with the PGA2311. The power supplied from the Digital/Analog separated regulator with one 7VAC X 2 transformer. So they both D/A also from the same transformer but difference regulators for each part and the ground joined together.
I found that it working quite smooth and almost no noise there. But the mute not function very well all the time. Once I muted it and it never get back. I need to restart everything. This module working with the LM3875 as a passive preamp. Sometime it will mute itself even haven't click the Mute button. I am using the mute function inside the the chip.
I am using the same software and similar layout with the PGA2320 but nothing goes wrong.
I would like to know is it the problem of grounding or just happen in 2311? Should I put the 0.1uf cap between the DGND pin and the ground? What should I do? I built serval piece but problem still there... Please advise! Thanks!
Hello Matthew,
Sorry to hear that you're experiencing this issue with the mute function of the PGA2311. Can you please provide a full schematic of your PGA2311 circuit so I can verify there are no major issues?
Best regards,
Ian Williams
Linear Applications Engineer
Precision Analog - Op Amps
Hello Matthew,
Thank you for posting your schematic. I have some follow-up recommendations and questions for you.
Best regards,
Ian Williams
Hi Ian,
Thanks for your quick reply.
1. In fact I do using the 100uF for decoupling. Also I have the 0.1uf directly solder on the power pin of PGA2311
2. No.... I am using the software one.
3,4.That means for this issue usually cause by the DC-offset problem from the source? In fact I using the ecap replace the 220R for the input cap. So is it good enough? I think that would be good enough for blocking, right? Or I need to add kind of the network for it? The input network is very simple. The transistor only for driving the relay as the selector.
5. Got it! But I don't really understand why the PGA2311 will suddenly no sound like muted when it playing for a while. It will get back after I switch it off and on again.
The output of the PGA2311 connected to the input of the LM3886 through the 330R and after the 330R will have the 22k to ground as load before the input pin of the LM3886...
Looking forward to the advise soon! Cheers!
Regards,
Matthew
Hello Matthew,
Best regards,
Ian Williams
Hi Ian,
Thanks for the help.
The problem happened with the AC coupling e-cap. The e-cap replace to the 220ohm at the day one already! The e-cap is 10uf 16v so I think it is good enough. I will check the voltage on those pins later.
I would like to know is the PGA2311 usually just took within 100mA for each voltage input? I am using the 10VA 7VACX2 should be good enough for this I think... right?
Regards,
Matthew
Hello Matthew,
In general, the current on any op amp input pin should not exceed 10mA. Any more current than this is likely to cause damage to the IC.
Best regards,
Ian Williams
Hi Ian,
I tried to reach the issue of the mute this few days. I found that it just working fine and can mute quite well at the beginning likes first 10 hours. Then if you keep it running after few hours it and trying to mute this. It possibly not coming back again. Then I checked the supply voltage when the issue happened. All are fine (4.95V to VD, 4.95V to VA+ and -5V to VA-).
I also found that there will have the very slightly sound like "deeeeeee" when the mute is fault. When it is working fine it will just have a very low volume of the music there... I would like to know what will it be? Thanks!
Regards,
Matthew
PS: The same controller working completely fine with the PGA2320... Thanks!
Hello Matthew,
A device which works for some time but then fails is often a sign of electrical overstress (EOS). Can you verify that the input and output voltages and input currents of the part are kept within the recommended range given in the PGA2311 data sheet?
Best regards,
Ian Williams