8 Channel Class D Project TPA3122

BlaSe · 11th July 2011, 06:10 PM

Hi,

I'm working on a Board that should hold 4 of the TPA3122's in Stereo mode to power a speaker array. (multible boards are used to get a 4x4 or even bigger array)
I have finished the layout in eagle and I have some questions.

1. Is it allowed to sum the voltage stabilization caps to one or two bigger ones when having 4 of the amps on a small board?

2. Because of the limitations of the free Eagle version i am limited in space, so the GND that connects the components farthest from the supply have only a thin connection. Is that bad? ( I thouth about using a wire to strengthen the connection)

3. The board will actually be produced by a PCB manufacturer.
Can anybody see obvious errors on the board.
DRC only gives ma some stop mask errors.

Thanks for the help.
regards
Sebastian

killerbobjr · 12th July 2011, 03:47 AM

You're going to run into problems with heterodyning of the carrier frequencies through the rails with 4 chips. Even completely decoupling the power supply won't get you interference free output. You would need to have 4 separate power supplies and each amp isolated.

A better solution is to use 8x TPA3106D1 which can be used in a master/slave configuration for the oscillators. If you are limited in space, I'd go with one chip per board, jumpers for the master/slave oscillator links through twisted pair wires, use a single smaller local power supply cap, wide power traces, and a single PS board with big reservoir caps.

theAnonymous1 · 12th July 2011, 04:47 AM

Two large supply caps is a bad idea IMO. You need two per IC as close to the supply pins as possible. 4x 3122 on the same board is probably a bad idea as well.

I recently finished making a layout for 4x TPA3106D1 (synced) for use in my car. Just need to find time to make the board.

BlaSe · 12th July 2011, 04:01 PM

Quote:

Originally Posted by killerbobjr

Even completely decoupling the power supply won't get you interference free output.

how strong would that interferences be?
i'm not planing on getting the maximum power/volume out of the amps and i'm using very small speakers.

killerbobjr · 13th July 2011, 05:03 AM

If the frequency was in the audible range, you would constantly hear a tone or tones that won't go away. Do a search in this forum. There was another member who ran into this problem with two TPA3xxx parts on a board where he describes what he encountered.

BlaSe · 17th September 2011, 11:33 AM

Update:
Despite your warnings i built the thing....and see there. No Problems at all.
Works quite well with a simple switching power supply from a external harddrive.

So don't fear putting more than one Amp of this kind on one board.
Regards
S

12th July 2011, 04:47 AM	#3
theAnonymous1 diyAudio Member Join Date: Feb 2004 Location: Anonymityville	Two large supply caps is a bad idea IMO. You need two per IC as close to the supply pins as possible. 4x 3122 on the same board is probably a bad idea as well. I recently finished making a layout for 4x TPA3106D1 (synced) for use in my car. Just need to find time to make the board. __________________ "If you don't like funerals don't kick sand in Ninja's face." - Ninja

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
TPA3122 doesn't work	Joku	Class D	35	19th November 2011 02:07 PM
TPA3122 - not working. Nothing	aviatorbja	Class D	17	26th July 2011 06:10 PM
TPA3122	aditya	Class D	2	10th April 2011 10:23 PM
TPA3122 Groundings	Cyberzim	Class D	6	18th September 2009 11:28 PM
Class D TAS 5261/TPA3122	jash2008	Class D	13	3rd August 2009 05:35 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

12th July 2011, 03:47 AM	#2
killerbobjr diyAudio Member Join Date: Sep 2004 Location: killer	You're going to run into problems with heterodyning of the carrier frequencies through the rails with 4 chips. Even completely decoupling the power supply won't get you interference free output. You would need to have 4 separate power supplies and each amp isolated. A better solution is to use 8x TPA3106D1 which can be used in a master/slave configuration for the oscillators. If you are limited in space, I'd go with one chip per board, jumpers for the master/slave oscillator links through twisted pair wires, use a single smaller local power supply cap, wide power traces, and a single PS board with big reservoir caps.

13th July 2011, 05:03 AM	#5
killerbobjr diyAudio Member Join Date: Sep 2004 Location: killer	If the frequency was in the audible range, you would constantly hear a tone or tones that won't go away. Do a search in this forum. There was another member who ran into this problem with two TPA3xxx parts on a board where he describes what he encountered.

17th September 2011, 11:33 AM	#6
BlaSe diyAudio Member Join Date: May 2011	Update: Despite your warnings i built the thing....and see there. No Problems at all. Works quite well with a simple switching power supply from a external harddrive. So don't fear putting more than one Amp of this kind on one board. Regards S

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)