High Temperature Power Supplies

High temperature has several negative effects on the performance of your power supply. It is pretty clear that a high temperature environment can cause your supply to overheat. Since your power supply has a specific efficiency, energy will inevitably be wasted as heat (in watts), which will lead to an increase of ambient temperature within a system. This will decrease the reliability of the supplies’ components.

High temperature environments can also cause insulators to fail and mechanical connections to loosen. This happens as a result of high temperatures causing changes to material properties within a supply, like expansion, which can ultimately shorten the lifespan of the supply. As mechanical connections expand and loosen, the connectors can experience a thermal runaway due to increased impedance at the point of connection.

There are many applications and environments that pose threats to your power supply in terms of high temperature. The most apparent threat are those environments that offer restricted cooling options. Environments that have no moving air or offer little capability for heat sinking or high thermal impedance heat sink tend to have the highest temperatures. This means that a supply in any mobile environment, such as an automotive, railway, or robotics application, will face harsh conditions. External environments, such as the desert or warmer climates throughout the globe, will automatically have a higher temperature for the overall application, not to mention the increase in temperature when the supply starts to function.

Even if there are some forms of external cooling available to your power supply, high temperature can pose a threat to your supply. For example, if liquid cooling is being utilized, the whole supply is not protected from the dangers of high temperatures. Liquid cooling will only cool the components of a supply that are mounted to the cold plate, which means most of the components are left exposed to the high temperature environment. Mechanical packaging of the supply has to be closely addressed in these cases.

When Designing Your Project

If you know your end product will be in a high heat environment, there are a few questions you can ask during the design stages:

Is there any cooling method already available, such as moving air or liquid?
-If yes and moving air: How is the cooling method ducted over the supply? How many LFM are there, and at what temperature?
-If yes and liquid cooling: What is the temperature and flow rate of the liquid? What is the thermal impedance of any heatsink surface? How do you package the supply to make the best use of a cold plate?

Reminder: Special packaging or unique components may need to be used to make use of the cooling already available. This can impact the cost of your design.

-If no: move to the next question.

What can be done to combat high temperature if no cooling method is available?
-Am I able to add a heatsink if necessary? Heat sink will add to the size, weight, and cost of your supply.

-If yes: How will the heat of the supply change the temperature of the heatsink?
-If no: move to the next question.

Do we have the means to design something custom?
-A custom supply may be necessary if the other methods are not able to work. Higher efficiencies and custom packaging may benefit your design.

Pay close attention to the temperature ranges, guidelines for cooling, max temperature operation, and any de-rating information listed within data sheets. Also look at the efficiency curve of a power supply noting at which power level it is most efficient. It is best to choose a supply that will fall within “highest efficiency” point when used in your system. If your environment will prove to result in a temperature that is too high for a supply, consider a custom supply. Designers can often accommodate temperature needs more easily.

See our High Temperature Guide