What is the temperature range for the voltage regulator on the Arduino Uno? The chip appears to be an RXG 117-5, however, I can't find it in the right package. I thought maybe it was a special part made for Arduino only.
Thanks
Temperature depends a bit on the manufacturer, but most specify 0-125 degrees C, with 25-100 degrees C being the most stable range. I would not recommend getting these regulators that hot. You don't want to burn yourself. Under normal circumstances, they shouldn't get very warm though. If they do, you are either drawing too much current, or the input voltage is very high.
I think this is the part
or the NXP brand of the same thing.
125C is pretty hot no matter what tho.
It is reaching right around 95 degC. I am externally supplying 12V to the board through the Vin and GND pins. I chose 12V because I am using 12V elsewhere in the project and the product page said the limits of the input voltage were between 6-20V, but recommended that it was between 7-12V. It isn't pulling all that much current: ~200mA, maybe 300mA?
It isn't pulling all that much current: ~200mA, maybe 300mA?
So that puts the dissipation at 2.1W quite a lot of heat for a tiny package to ship out.
Those temperatures mention d by the others are not the package temperature but the junction temperature.
Have a read of this:-
http://www.thebox.myzen.co.uk/Tutorial/Power.html
There's an old rule-of-thumb that says, "If a part is too hot to touch, it's too hot". It's probably more accurate to say, "If you can hold your finger on it, it's not too hot."
I'd say if you can't hold your finger on it (or if you just think you might be pushing the temperature limits) you shoud think about changing your design.
The temperature on the datasheet is usually the internal junction temperature. The outside case temperature will be lower. There's a way to calculate the internal temperature based on the heatsink parameters and the thermal resistances, but I've forgotten the details, and it seems like there are always some unknowns for some of the thermal resistance values, or something unknown that you have to estimate.
And remember, the electrical energy dissipation causes a temperature rise. The part can get 20 degrees hotter on a hot summer day without air conditioning.
Where I work, we run our products for a week in a 50 degree C burn-in room before we re-test & ship. That usually weeds-out any early failures, but one time we had a wrong component in a voltage regular circuit causing it to overheat... The boards survived our burn-in, but some failed in the field. Once we discovered the problem, I found out the part was too hot to touch. This was a switching regulator, so it shouldn't have been warm at all!
w_schwalm:
It is reaching right around 95 degC. I am externally supplying 12V to the board through the Vin and GND pins. I chose 12V because I am using 12V elsewhere in the project and the product page said the limits of the input voltage were between 6-20V, but recommended that it was between 7-12V. It isn't pulling all that much current: ~200mA, maybe 300mA?
That's 10 times the current draw of the Arduino alone - use an external 5V regulator for your high current 5V
circuitry perhaps? A 7805 with a small heatsink would be appropriate.