Lm1875

[soundNERD]

I don't know too much about heatsinks, other than they take heat off of chips. Is the small heatsink below sufficient for the LM1875?

 

[jean-paul]

No, far from that. Use a proper heatsink that is able to keep the chip at a normal temperature at full load.

 

[soundNERD]

How about this?

 

[jean-paul]

Still too small.

 

[Netlist]

I don't know too much about heatsinks

Here's the datasheet for the LM1875.
http://www.national.com/ds/LM/LM1875.pdf
There's a lot of good info in it regarding heatsinks.
Search this forum as well. There are many threads talking about calculating them.
This is one example: http://www.diyaudio.com/forums/showthread.php?s=&postid=101358&highlight=#post101358

/Hugo

 

[soundNERD]

I have the datasheet, but all the equations and info about heatsinks make no sense to me. Can anybody explain to me some basic things about them?

My project is a surround sound computer speaker system.

Thanks, Mike

 

[autoexec]

just get 1 about the size of a couple of decks of playing cards

 

[JCoffey]

Or a heatsink from a PentiumII processor. My LM7886 integrated once I took it apart has a heatsink that size that both chips are attached to. I was kinda shocked, but it's never gotten too hot, so the LM1875's shouldnt need any more than that. I have access to quite a few of them here at work, since we're pulling all of our old PII pcs.

 

[jean-paul]

just get 1 about the size of a couple of decks of playing cards

That's better.

 

[soundNERD]

so, this is a little overkill, right? i mean, it can keep a 3886 cool... or am i wrong. If you cant read the ruler, it is 4 and 1/8 inch wide, about 2.5 inches deep and a little over 3/4 inch tall.

 

[JoeBob]

soundNERD, the heatsink you refer to may be spread out over the dimensions you quoted, but that is nowhere near big enough. You need a heatsink that has a solid base and fins coming out of it, there needs to be alot more solid metal and surface area for the heat to dissipate than the sink you posted a picture of. You probably won't find heatsinks big enough at digikey or the likes, nor many local electronics stores, try looking at metal shops or the best in my opinion, surplus stores.

 

[Peter Daniel]

Aluminum plate 3 x 6 will do.

 

[JoeBob]

But how think a plate? If you use 1mm think Al, I doubt that'd be enough.

A small heatsink or a (relatively) think plate would work fine for you, just don't use anything that's stamped steel, you'll just toast your devices.

 

[Peter Daniel]

1/8 or 1/4 should work fine. It may get warm, but shouldn't be too hot.

 

[soundNERD]

Sorry. Yet again, I forgot to attach the picture. Here it is.