PIC temperature, when is it too hot

[Demon]

16F18877 specifically

There's a bunch of charts in the datasheet with fancy curves, as well as the 85C limit for extended operation (section 37.2).

1. At what point is it recommended to start glueing a heatsink on these puppies?

2. Is there a rule of thumb? Or is it arbitrary?

3. And if you do cool PICs, what adhesive do you use? What heatsinks?

[tumbleweed]

In all the years I've been using PICs I've NEVER had one get even slightly warm.
They usually only pull a few 10's of mA's max, but I suppose if you had all the IO pins trying to drive too much current it might increase the temp a bit.

Is yours getting hot?

[pedja089]

There is max current per port, and Vdd pin. That current is much lower than sum of all 20mA per pin. So you should not try to pull 20mA from each pin...
Pic should not get warm at all. Power disipation should be in mW.

[Demon]

There is max current per port, and Vdd pin. That current is much lower than sum of all 20mA per pin. So you should not try to pull 20mA from each pin...
Pic should not get warm at all. Power disipation should be in mW.

Good idea, I'll get a current reading on both power pins.

[Ioannis]

According to the 16F18877 data sheet, the Absolute Total Power dissipation is 800mW, which is quite a lot!

Absolute Max current on any standard pin +/-50mA, but this does not mean you can source or sink on all pins at the same time that current. You have to stay lower than 800mW total.

In any case these are impressive numbers but for good reliability better stay lower.

Ioannis

[HenrikOlsson]

37°C is nothing. At twice that I'd start thinking if there's something wrong.

[Demon]

In all the years I've been using PICs I've NEVER had one get even slightly warm.
They usually only pull a few 10's of mA's max, but I suppose if you had all the IO pins trying to drive too much current it might increase the temp a bit.

Is yours getting hot?

2/3 the pins are sinking inputs, the rest are unused for now.

Thermal cam says 36.4C.

I didn't have a thermal cam before, so I have no clue what "normal" is. It is a busy PIC though, 2 ADC and 2 PWMs.