tda7292 bridge

[pra3718]

Is it possible ? I did not find in datasheet. I think it should bridge similar to tda7265. Want to know more for SOA, Maximum power supply in bridge mode & Output in bridge mode.

Regards.

[Boscoe]

It is in the datasheet. Max 16V supply and a 50W max output into 4ohm.

[AndrewT]

Originally Posted by Boscoe

It is in the datasheet. Max 16V supply and a 50W max output into 4ohm.

that requires each half of the bridge to deliver 25W into 2r0. That is equivalent to 10Vpk and 5Apk into a 2r0 resistor.
A real 2ohm speaker can demand upto 3times the resistor current.
Can a 7292 meet that value (15Apk) of transient current demand?

[Boscoe]

It's a stereo 25W + 25W chip @4ohm I don't know wether it's capable of driving into 2ohm.

[pra3718]

Boscoe, This thread is related to TDA7292 (40W+40W). I put the example of TDA7265.

AndrewT, If bridge is possible with TDA7292, output should be 70-80Watts in 8Ohm driver. But I don't now the maximum power supply in split configuration. 24VDC (+/-) must be okey. What ?

[AndrewT]

Boscoe and Pra,
swot up bridged configuration.

I'll start you off by restating what is posted above.

A pair of 20W into 8r0 amplifiers when bridged will deliver a maximum of 40W into 16r0.

Turning that rule back to front:
A bridged amplifier that delivers 40W into 16r0 must use a pair of amplifiers capable of delivering 20W into 8r0.

Now extend that to a bridged amplifier that is supposed to be 50W into 4r0.
Each half of the bridged pair must be capable of 25W into 2r0. That is just what is required if the load is a 4r0 resistor. See later what is required for a reactive 4ohm speaker.

But, we should know that a speaker is a complex impedance and that current demand of a crossed over multi-way speaker can be very much higher than a simple resistor.
I allow for 3times the current demand, I have seen a report that shows three very different speakers that demanded more than 5times the current that an equivalent resistor would draw.
I would suggest you allow a minimum of 2times.
So a 4ohm amplifier must be capable of supplying current into a 2r0 load while still maintaining adequate output voltage. The bridged half must be capable of driving significant current into 1r0 while still maintaining adequate voltage to drive the load.

I'll stay with my adopted target of 3times. It is not difficult to achieve with discrete nor expensive.
It is very difficult to achieve with any integrated chipamp when speaker impedance is less than 8ohms.

[pacificblue]

The TDA7292 has a current limit of 4,5 A. It is specified for 4 Ohm per channel with ±18 V rails which means it should only be bridged into 8 Ohm with the same rail voltage. That should be good for 48 W at 1 % THD. Heatsinking may become an issue.

[pra3718]

Thank you, Should I copy the bridge schematic from tda7265 datasheet for tda7292 bridge ?

That should be good for 48 W at 1 % THD.

And about 10% THD 62W output power with ±18 V rails.

[AndrewT]

no wonder the distortion results are so bad for driving a resistor.
The powers reporting 1%THD and 10% THD are asking for output currents of ~4.9Apk and ~5.5Apk respectively.

How much worse will it get if we replace the resistor with an equivalent impedance speaker?

This is silly.
I can never recommend using bridged chipamps driving lower impedance speakers.

[pacificblue]

Originally Posted by pra3718

Thank you, Should I copy the bridge schematic from tda7265 datasheet for tda7292 bridge ?

Let's say you shouldn't, but you could.

Originally Posted by AndrewT

This is silly.

It would certainly be more promising to do something about the speakers instead of trying every chipamp that is available on the Indian market in every possible and impossible configuration hoping for a miraculous sonic improvement that won't come.