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-   -   TDA7492 _ heatsink is mandatory ? (http://www.diyaudio.com/forums/class-d/283895-tda7492-_-heatsink-mandatory.html)

ginetto61 16th December 2015 06:45 AM

TDA7492 _ heatsink is mandatory ?
 
Hi !
i have a little amp built around the TDA7492 chip.
I opened it and i saw that the chip is exposed, i.e. without heatsink.
I saw other amps with an heatsink on it.
Is an heatsink mandatory ?
I will post the pictures of internals because i would like to operate it a 20VDC (i have a nice quality PS with this voltage).
Instead i see two caps rated 16V ... that i am about to replace with 2x25VDC/4700uF.
However the sound is nice ... quite musical.
Thanks and regards, gino

JonSnell Electronic 16th December 2015 09:40 AM

The pcb will take any heat away from the chip. The fitting of a heatsink on the top of the chip keeps it cooler but not needed due to low power dissipation. If you look at the underside of the chip, that is where the heat needs to be dissipated; through the pcb.
http://html.alldatasheet.com/html-pdf/470923/STMICROELECTRONICS/TDA7492P/1945/1/TDA7492P.html

ginetto61 16th December 2015 09:55 AM

Quote:

Originally Posted by JonSnell Electronic (http://www.diyaudio.com/forums/class-d/283895-tda7492-_-heatsink-mandatory-post4549610.html#post4549610)
The pcb will take any heat away from the chip. The fitting of a heatsink on the top of the chip keeps it cooler but not needed due to low power dissipation.
If you look at the underside of the chip, that is where the heat needs to be dissipated; through the pcb.
http://html.alldatasheet.com/html-pdf/470923/STMICROELECTRONICS/TDA7492P/1945/1/TDA7492P.html

Hi and thank you so much for the very kind and helpful advice.
Actually i see copper under the chip. I guess if for the heat dissipation ?
The recommended supply voltage is now 12-15VDC but i know that the chip can take 20VDC and i would like to do this.
I have already at hand some low noise SMPS to try.
I will have to replace two ps caps inside rated 16V.
I will post a picture anyway to show the internals.
All considered the sound is nice for such a little chip. Quite amazing actually.
Thanks again, gino

wwenze 16th December 2015 09:31 PM

12V class-D amps don't require a heatsink, just some metal on the PCB will do.

20V will require a heatsink.

Remember to find and remove any overvoltage protection diode.

ginetto61 17th December 2015 05:37 AM

Quote:

Originally Posted by wwenze (http://www.diyaudio.com/forums/class-d/283895-tda7492-_-heatsink-mandatory-post4550254.html#post4550254)
12V class-D amps don't require a heatsink, just some metal on the PCB will do.
20V will require a heatsink.
Remember to find and remove any overvoltage protection diode

Hi and thanks a lot for the very helpful advice.
I will keep the voltage low and no modifications ;)
i do not want to fry this little nice thing.

I have an opinion. A general one. About amplification.
Usually a power amp gives its full power with JUST 1V at the input.
Still i see many line preamps having no problem to output 10 and even 20V clean and undistorted, with a complete regulated voltage supply.
The same applies to these nice class D units.
They should be used as VAS and driver stages for a power buffer with very little voltage gain, leaving to the buffer the heavy work of driving the speakers.
I understand these chips have limitations in current output.
The resulting sound could be phenomenal and such an amp could drive everything without big problems.
I believe a lot in power buffer but they seem extremely rare.
Maybe there is a technical reason ?
Thanks again, gino


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