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I have AD811 in my application that works just fine but as it is working in +/-15 v supply at around 14.5 mA, it's power is around one third of watts. It is hot when touched. I checked if this is a malfunction in this website and contacted Analog Devices Technical support and I am sure that this is a normal behavior of this device.

Now I am thinking about a cooling method for this device but as this DIP package has no where to attach a heat sink, I thought about some options like these ( regarding the device works in high frequency up to 50MHz):

  1. Using a fan: fan's motor may impose some noise

  2. Putting a flat heat sink on top of the device , attaching it with silicon paste and grounding it

  3. Using a thermoelectric coolant element.

I have never heard about cooling methods for DIP packages especially in high frequencies, I want to know if there is any standard method for that.

starblue
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Aug
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    I assume this is for a DIP-8 ... Aavid Thermalloy makes a small slide-on heatsink for that package: http://www.aavid.com/products/standard/580100w00000g Not sure if that will provide enough cooling or not, but at appx 1/3W I doubt that you need much. A little thermal grease and a little airflow would help a lot. – Tut Oct 15 '13 at 17:16
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    Some thermal relief pads and a proper copper plane (maybe on both layers) surrounding the DIP may be enough. – Rev Oct 15 '13 at 17:20
  • @Tut I know this power dissipation is not that much but as it is hot in touch, I am thinking about reduced life time span of the device. – Aug Oct 15 '13 at 17:41
  • @Tut On the other hand I want to know if the device you mentioned would impose noise to my device or not? – Aug Oct 15 '13 at 17:48
  • I agree with you about life span. The point I was trying to make is that it will not take much of a heat sink. Regarding noise, I don't really know, but it will probably have to do with your circuit impedances and nearby noise sources. The best way to tell is to try it. It is after all a slide-on device. – Tut Oct 15 '13 at 17:54
  • I am not a member of IEEE, but if you have access: [The influence of heat sink on noise susceptibility of IC](http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=750091) may be of some use. – Tut Oct 15 '13 at 18:00

3 Answers3

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With the much reduced use of DIP ICs, few component retailers offer DIP heat sinks any more (and possibly few of the younger electronic circuit designers know about the stuff!). However, if you are looking at personal / DIY use, glue-on DIP heat sinks in anodized aluminium are available, often as "new old stock", on sites like eBay, and surplus vendors.

For instance, I found this on eBay for under $1:

DIP heat sink

While it is designed for 14 to 16 pin DIPs, it is trivial to chop it down the middle and use half for an 8-pin DIP.

Thermal paste between the heat-sink and the IC would be useful, or one could use peel-and-stick thermal paste pads for convenience:

Thermal paste pad

Some form of clamp would also be needed to hold down the heat sink, if glue-on isn't good enough.

Alternatively, 2-part and slide-on heat sinks for DIP used to be quite common, and can still be found as "new old stock". These eliminate the need for a clamp:

2-part DIP heat sink

However, these heat sinks are not as convenient to use for a smaller DIP, such as an 8-pin package.

Finally, sometimes one would sand the face of a metal coin flat, then clamp it onto a DIP IC, as an interesting-looking heat sink. End of history lesson :-)

Anindo Ghosh
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    Contra to what Olin says below, there are sometimes good reasons to add heatisinks to DIP or SOx packages. Even though you can't find the Tjc through the expoxy/plastic ("mold compound") in the datasheet, it usually 1/3 to 1/4 of that to air. You can easily double or triple the chip's tolerable wattage, extending its SOA and/or projected lifetime, which in some cases is worth it. Some manufacturers have more recently caught up with the idea of heasinked SO chips, e.g. http://www.onsemi.com/pub_link/Collateral/AND9014-D.PDF (which is heatsinked on both sides, actually.) – Fizz Sep 07 '15 at 14:53
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DIP packages aren't really meant to be cooled, other than to make sure the ambient temperature is reasonable.

If you can touch the chip and it feels hot, then there is no problem. If it were really hot, you'd burn your finger.

Relax. Don't worry about it.

Olin Lathrop
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  • well, the ICL8038 is well known, to be quite hot while not performing anything special and it's only availible in DIP cases. – Jakey Aug 01 '18 at 23:53
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There are a lot of variables that can effect your decision. Is the chip under 160 deg fahrenheit at maximum duty cycle? If it is youre probably fine. But sealed environment, surrounding ambient temperature and other factors can cause thermal overrun in an otherwise acceptable circuit. If you cant keep it under 160 deg find a heatsink.

Scott Dowdy
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  • Degrees F is inappropriate in this application. All datasheets I've seen specify temperature in degrees C. F can be a nicer unit for human-perceived temperature, but use C or K for engineering or science. – Olin Lathrop Aug 02 '18 at 10:45