Help with my TPA3122D2 amp circuit

[Jasper1702]

Hello all , i have a problem with my TPA3122 ic based circuit , The amp works all ok with my ipod when powered from bench power or 12v battery but when i conect the amp and a small dab radio to the same power supply the amp does not play the dab it just clicks
I've tried changing bits on the amp but its the same ,if i unplug the 3.5 plug out off the dab back in to the ipod and repower on its plays perfect.
The ground for the analog side is separate from the power side and star connected
Can anyone help

 

[DUG]

Are there capacitors on the input line of the 3122 amp?

 

[Jasper1702]

Yes 1uf ceramic
Ive tried the bridged and stereo it does the same thing
When I power the dab from a different power supply it works OK
?????

 

[Jasper1702]

Well I gave up on that circuit ,I made a new PCB and used a big ground and smd to help stop interference
All is a lot better now only the slightest hum with no volume
But I have a problem with power on click, it clicked about three time and starts playing all OK is there a way to stop the clicking on startup ?
I used 1 uf on inputs
0.1 uf on pins 1& 20 , 10 & 11
1 uf on 6 & 9
1 uf & 0.1 uf on 16,17
470 uf on power inputs 1 ,10
0.22 uf on 12,13 & 18 ,19
22UH output with 0.680 uf and 1000 uf to block DC to speaker
Hope someone can help me
Thanks

 

[DUG]

What have you got on pin 2?

Take a look at putting an RC delay to that pin so it is held low for a short period of time.

 

[Jasper1702]

I have pin 2 going to power and pin 3 to ground
Thanks ill try that
Is there a better capacitor value for pin 16, 17 than 0.1 uf and 1 uf that i have in my board

 

[DUG]

...
Is there a better capacitor value for pin 16, 17 than 0.1 uf and 1 uf that i have in my board

I usually use what the data sheet suggests.

 

[doctormord]

It depends on your current loop at 16/17. If you go really² close to those pins, 1uF is enough (low esl X7R MLCC), but have a look for dc-bias.

 

[Jasper1702]

I'll have another look at the data sheet
Thanks all !

 

[Jasper1702]

Here is a pic off my new circuit board

 

[doctormord]

Cool story.

 

[DUG]

Add some good stranded wires or copper strap from pin 11 to 20.

Having the two output ground sections connect via the AGND is not a good idea.

 

[Jasper1702]

Ok thanks
I'm going to make a new board this weekend so I'll do the changes to that
Thanks for the help ++++

 

[Jasper1702]

Hello again i made a new pcb to separate the power ground and audio ground and that's all good thanks !
I still had the clicking nose on power up, sometimes it clicked a bit or a lot.
Anyway after a lot off messing with parts i discovered pin 9 is the problem and quite fussy on witch capacitor is used.
Hope this helps anyone having the same problem.