LM380 Heat Sink considerations

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LM380 Heat Sink considerations

Postby Shango » 09 Jan 2018, 21:36

Hi all,

I'm working up a design for a 2xLM380 bridged practice amp. Planning to run it at 18v, so I'm expecting to need some kind of heatsink for each chip.

Questions:

-Is it a sure thing the chips will need a heatsink running at 18v?

-Anyone have a design or source for one? I'm pretty much a complete newb at making/attaching heatsinks since until now I've really only used your standard pedal design ICs and LM386's.

Would a large ground plane attached to the heatsink pins of the LM380 do anything to help dissipate heat?

Here's the schematic I'm working from, (changing the preamp stage):

download/file.php?id=18526&mode=view
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Re: LM380 Heat Sink considerations

Postby tonyharker » 09 Jan 2018, 22:39

Have you looked at the datasheet? There is a drawing of a heatsink therein.
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Re: LM380 Heat Sink considerations

Postby Shango » 09 Jan 2018, 23:15

tonyharker wrote:Have you looked at the datasheet? There is a drawing of a heatsink therein.


I have seen it. Unfortunately, it's not really much to go on for someone completely new to heat sink building/implementing. In fact, I'm not entirely sure how it attaches to the chip itself, or if I was, how to source the material/build it.
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Re: LM380 Heat Sink considerations

Postby FiveseveN » 09 Jan 2018, 23:52

Shango wrote:I'm not entirely sure how it attaches to the chip itself, or if I was, how to source the material/build it.

Caption next to drawing: "Soldered to Pins 3, 4, 5, 10, 11, 12". The chip is designed to use the PCB copper for heat sinking, and figure 6 promises 2.5 W dissipation in this kind of typical application. So yeah, big ground plane without solder mask and you'll probably be fine. If not, just make the "wings" out of some sheet metal (Cu or Al ideally) and solder/screw them right next to those ground pins. The point is to add some more mass for heat to go into, the exact shape and such is not important.
Ignorance more frequently begets confidence than does knowledge. (Charles Darwin)

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Re: LM380 Heat Sink considerations

Postby Shango » 10 Jan 2018, 02:56

FiveseveN wrote:
Shango wrote:I'm not entirely sure how it attaches to the chip itself, or if I was, how to source the material/build it.

Caption next to drawing: "Soldered to Pins 3, 4, 5, 10, 11, 12". The chip is designed to use the PCB copper for heat sinking, and figure 6 promises 2.5 W dissipation in this kind of typical application. So yeah, big ground plane without solder mask and you'll probably be fine. If not, just make the "wings" out of some sheet metal (Cu or Al ideally) and solder/screw them right next to those ground pins. The point is to add some more mass for heat to go into, the exact shape and such is not important.


Thanks! This helps a lot.
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