I am connecting a circuit for Texas Instruments TPA3125D2 Class-D Aplifier.

Datasheet here: http://www.ti.com/lit/gpn/tpa3125d2

The circuit design is here: enter image description here

The circuit that was tested is not on pcb but on a solderless breadboard.

The problem is, that ALL I get, is some kind of bumping sound in the output speaker which does not depend on the input (no matter if input is connected or not, the output is the same - some kind of pulsation).

I do not get any output except this mentioned bumping sound.

That would be a great help, if someone experienced enough could review this scheme and give some critics or comments, on what is wrong here?

  • \$\begingroup\$ Have you followed the recommended PCB layout? It sounds like oscillation caused by poor layout. \$\endgroup\$ – Leon Heller Apr 18 '19 at 8:55
  • \$\begingroup\$ No, I did not, but the circuit I had connected, was made on the bread board with wires. May this be the problem? \$\endgroup\$ – Vytautas Apr 18 '19 at 8:58
  • \$\begingroup\$ You need to construct it on a PCB. A solderless breadboard is a waste of time with that type of amplifier. \$\endgroup\$ – Leon Heller Apr 18 '19 at 9:05
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    \$\begingroup\$ The suggested output filter uses 33uH inductors and you apparently have 0.33uH parts (0.01 of specified size) so the output filter will not give the response required. \$\endgroup\$ – Peter Smith Apr 18 '19 at 9:08
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    \$\begingroup\$ It's probably oscillating because it isn't on a PCB. You won't hear anything else. \$\endgroup\$ – Leon Heller Apr 18 '19 at 10:03

This is a pulse circuit. It should have very short wires generally, thick GND and coupling capacitors to keep the voltages stable during the transients. U2 needs them, too. Otherwise nobody can quarantee anything(except it will not work). Obviously you have none of these.

The datasheet has detailed guidance for it. What capacitors you possibly have inside your power supply, does not help because there's a long wire to them. One centimeter or less is good.


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