PCB trace thickness for audio??

[nigelwright7557]

Thin tracks should be fine for audio pre amp levels.
However they are mechanically not as strong so if you need to de-solder something you can start burning of thin tracks.
I tend to use 2mm tracks and thicker for power lines.
It costs nothing to leave copper on.
I tend to use ground planes or copper pours to keep more copper on the pcb.

 

[aditya]

Why not just put all the supplies on the soft start? Then they'd come up at the same time.

I'm not intimately familiar with the PGA2311, but I am familiar with IC design. If you bring up one power supply but not the others, you run the risk of turning something on through the ESD protection devices on the chip. That's usually not a recipe for anything good. I've seen cases where chips have latched up and pulled very high supply current if one supply was significantly delayed.

To know for sure I suggest asking on TI's E2E forum. They're pretty fast to respond usually.

Tom

I had a standby feature and wanted to use it.

Other option “noisy” was to use the analog 0-12 0-12 to get the PGA’s digital supply also.

And the last option would be to let go of the standby option and as you suggested put everything via the soft start

 

[tomchr]

It costs nothing to leave copper on.
I tend to use ground planes or copper pours to keep more copper on the pcb.

Exactly. You pay for the copper anyway so you might as well use it.

Tom

 

[tomchr]

Other option “noisy” was to use the analog 0-12 0-12 to get the PGA’s digital supply also.

No harm in that. It'll have a regulator between it and the 2x12 V. Besides, when the PGA is not changing gain it's digital circuitry should be static -> no added noise.

Tom

 

[aditya]

No harm in that. It'll have a regulator between it and the 2x12 V. Besides, when the PGA is not changing gain it's digital circuitry should be static -> no added noise.

Tom

I will try this.

Also I would like to post my layout for a review , I don’t thinks well made.

 

[tomchr]

Nothing stops you... I suggest that you follow the layout guidelines on page 15 of the PGA2311 data sheet before posting, though.

Tom

 

[aditya]

Nothing stops you... I suggest that you follow the layout guidelines on page 15 of the PGA2311 data sheet before posting, though.

Tom

I have followed that but I for other things

 

[analog_sa]

Have been using 500VA toroidal transformers with zero measures to limit start up current for ages. Stubborn b@stards seem dead set to outlive me.

 

[aditya]

Have been using 500VA toroidal transformers with zero measures to limit start up current for ages. Stubborn b@stards seem dead set to outlive me.

Hahahahaa that was a funny last line but be safe 😬👍😁

 

[aditya]

Nothing stops you... I suggest that you follow the layout guidelines on page 15 of the PGA2311 data sheet before posting, though.

Tom

The reason I shared is because I hear hiss from the tweeters when I am at gain of 10 from PGA2311 and I would like to remove it

 

[analog_sa]

The reason I shared is because I hear hiss from the tweeters when I am at gain of 10 from PGA2311 and I would like to remove it

This may just be amplified noise already present at input. Without knowing the total gain in your system it's impossible to point a finger at the 2311. Do you listen to music at gain 10?

 

[aditya]

This may just be amplified noise already present at input. Without knowing the total gain in your system it's impossible to point a finger at the 2311. Do you listen to music at gain 10?

The opamp at the input is at a gain of 0.7db

And this hiss is with input shorted

 

[tomchr]

I doubt the hiss is anything due to the layout, at least if you have proper decoupling in place. I would measure the hiss (RMS output voltage) before redoing the layout. If the circuit meets spec, you won't gain anything from a layout tweak.

Tom

 

[aditya]

Could be coz I am using 7805 and 7809 and should use LM317 / 337 ?

 

[tomchr]

Could be that you should measure. Build an LNA. Use a multimeter. Ya know... Just a thought.

Tom

 

[analog_sa]

Could be coz I am using 7805 and 7809 and should use LM317 / 337 ?

Not likely at all. Can't you take measurements with a sound card? It will take a lot less time than speculating. Most decent soundcards are ok down to -120db.

 

[aditya]

Not likely at all. Can't you take measurements with a sound card? It will take a lot less time than speculating. Most decent soundcards are ok down to -120db.

Ok it is new to me will try it

 

[popchops]

I saw this recommendation for PGA2311 suggesting two ground planes, top AND bottom. Is that necessary? Is there any benefit in two overlapping ground planes? https://e2e.ti.com/support/audio-gr...ga2311-digital-noise-in-analog-section-output

Pops.

 

[aditya]

I saw this recommendation for PGA2311 suggesting two ground planes, top AND bottom. Is that necessary? Is there any benefit in two overlapping ground planes? https://e2e.ti.com/support/audio-gr...ga2311-digital-noise-in-analog-section-output

Pops.

Another question to it is - what is the spacing required between the two planes

 

[tomchr]

I saw this recommendation for PGA2311 suggesting two ground planes, top AND bottom. Is that necessary? Is there any benefit in two overlapping ground planes? https://e2e.ti.com/support/audio-gr...ga2311-digital-noise-in-analog-section-output

You're paying for the copper anyway. You might as well use it. I'd follow the advice given in the third post in that thread. Do be careful with the return paths for the digital traces. If you keep the analog circuitry to one side of the PGA and the digital to the other and joint the two grounds under the PGA you should be good.

Tom