# How do digital potentiometer data sheets define maxmimum power disipation?

I am new to digital potsentiometers, but I would like to use one in a design.

I have been looking at several digital potetiometer datasheets and I kind of expected to see some kind of maximum power dissipation value that needed to be respected for all settings.

Is that parameter described in a digital potentiometer data sheet in another fashion? Can anyone explain how to understand the upper limit of power dissipation in a digital potentiometer?

• I expect the power dissipation to decrease as the resistance decreases because you are using fewer resistors and concentrating more power into them. Similar to a sliding ceramic rod resistor: if you're passing current through both far ends you're dissipating power using the entire length of the rod...but as you decrease the resistance by moving the terminals closer together you are dissipating power over a smaller and smaller length of the rod. Commented Mar 15, 2021 at 21:31

Lets use the AD5246 as an example. It has a θja of 340°C/W. If we were to apply 5V between the wiper terminal and terminal B and set the resistance to 1K, then the power would be $$\5^2/1000=0.025W\$$. Next we have multiply by θja: $$\0.025*340=8.5\$$. So the temperature of the device would increase by 8.5°C i.e. if the ambient temperature was 25°C the temperature of the device would be 33.5°C. This would be fine for the device.
Now lets say we change the resistance to 50instead of 1K. Lets follow the same calculations. $$\5^2/50=0.5W\$$, $$\0.5*340=161°C\$$. This is a lot higher than before. For 25°C ambient, the temperature would be 186°C! That is really hot and would definitely burn out the device. The operating temperature of this device is only up to 125°C.