TDA7293's "protection"

[peufeu]

The datasheet says this circuit has full protection against almost anything...

Today I accidentally shorted the output while running a full power sinewave test.

Well, I got flames, about 10cms. high, everything turned into charcoal, half of the bootstrap capacitor evaporated, the works.

The other channel died in sympathy too (I don't know why...)

This was quite spectacular !

So don't trust the datasheet too much... !

[StratoFan]

Peufeu, I have problems with datashet too but while I tested my bridged poweramp with 2 7294, I have same situation, I shorted the output to the ground for longer time via jack output (without heatshink), but the protection works well and finaly I have no problem. How was the +-Vs while you tested?

[quekky]

that's odd, my datasheet (from st) says "SHORT CIRCUIT PROTECTED (WITH NO INPUT SIGNAL APPLIED)" Where did you see that it have full protection against almost everything?

[StratoFan]

When I made this failure with 7294, I have input signal - not small. But the power supply was only +-14V while testing.

[Easyamp]

I stopped using tda729X for opa541's becuase I couldn't treat them good enough and they kept blowing out on me.

They don't have any real short circut protection, you can tie the outs together with no signal but who cares I can do that with my Rod Elliot P3A amp which has no short pro at all. Any type of failure in the load or one zig when you should of zagged and POOF.

I've had good succes with TI's chips they seem indestructable, and while I do love the sound of the TDA's they are just to sensitive for me.

Happy new year

[peufeu]

The TDA7294 Datasheet says :
SHORT CIRCUIT PROTECTION

The TDA7293 Datasheet says :
SHORT CIRCUIT PROTECTED (WITH NO INPUT SIGNAL APPLIED)

And it's almost the same circuit inside... hum hum hum.

And I still think the TDA sound undetailed, dark and a bit of "mosfet mist" too.

[Easyamp]

It may say short circuit protection on the sheet, but with a no signal allpied disclaimer, it's not a very practical short circuit protection. If they only had National spike circuitry.

I do believe if your looking to get away from chip amp shortcomings you might want to go discrete, you have more control on the performance.

I wonder how nOrh got away with selling an amp (le amp) that would blow up in your face if you shorted the leads while it was working. It looks like they have stopped selling it, I guess that's one way.

Just to prove I'm not a chip amp hater I just recently put together an lm3875 stereo board. I have since bolted it to a heatsink but have yet to find an eclosure.

http://www.easyamp.com/img/lm3875/amp-top.jpg

[peufeu]

I know, I should go discrete, but here I needed many channels quick for an active crossover. I'll probably build the same ap in discrete later...

You mean the LM3875 will resist to a short on output with signal ? And there'll be no flames ?

[Easyamp]

You mean the LM3875 will resist to a short on output with signal ? And there'll be no flames ?

That's a good question, I'm to timmid I think to find out.

Do you not agree though that national semi's patented spike protection is a better safety mechanism then the TDA's.

If it works like national claims you should be able to short the leads while it's working and get away with it.

They give an example of this in there spike notes

http://www.national.com/an/AN/AN-898.pdf#page=3

on page 2.

Have you smoked an lm3875?

[peufeu]

I bleq an LM3876 by making a short, but I don't know which pins shorted. No flames, but it didn't work anymore.

Anyway I discovered the Mute input of this chip is a can of worms so better use the LM3875 !