Voltage regulators are supposed to step the voltage down to meet the voltage requirements of a particular device. However, many people think that they have bad regulators because these tools keep overheating or shutting down. As it turns out, such behavior is normal.
Any tool that a current flows through is expected to generate some heat. The amount of heat generated will depend on the efficiency of the tool and the amount of current it draws. In the case of voltage regulators, your question shouldn’t be whether or not a voltage regulator is hot but, rather, whether or not it is too hot.
Are Voltage Regulators Supposed to Get Hot?
Once the voltage regulator is in place, it will step the voltage down as required to suit the sections that need a lower voltage. This process generates heat. It can’t be avoided. When the regulator steps the voltage down, the difference between the higher input voltage and the lower output voltage is dissipated as heat.
Yes, voltage regulators are supposed to get hot. You will find these tools in systems with sections that have different voltage requirements. In such cases, it is easier to provide the highest voltage possible.
You primarily see this in linear voltage regulators, which is why they are not very efficient. They waste far too much energy as heat. Even with a moderate current, they can heat up at a faster rate than some people expect.
Switching voltage regulators are technically superior. At the very least, they are far more efficient. However, they will also become hot, especially when the switching frequency increases. Simply put, because of the work they are expected to do, it is perfectly normal for voltage regulators to produce heat.
However, there is a difference between a hot regulator and one that is overheating.
How Do You Know That a Voltage Regulator is Overheating?
Many voltage regulators will keep working even when they overheat. You cannot necessarily rely on them to shut down once the temperatures grow to disturbing levels. This is because they are designed to produce a specific voltage output.
So long as they check this box, the regulator has no reason to assume that things have gone wrong. Before you can figure out what causes a regulator to overheat, you need to find out what counts as overheating.
This isn’t an issue if your regulator has a mechanism that shuts the device down once it exceeds safe temperatures. But as was noted above, many regulators do not have this feature. You have to look at the datasheet to ensure that your regulator has this ability.
If it does not have such a mechanism, you can still find the answers you want in the datasheet. The average manufacturer will tell you the appropriate temperature range within which the regulator should operate.
If the regulator exceeds that temperature, then you can rightly conclude that it is overheating. Of course, you can save some time by simply touching the regulator, though this isn’t always safe. If the regulator is so hot that touching it burns your skin, you can safely conclude that it is overheating.
To be more specific, if the regulator is so hot that you cannot touch it for more than a second or two, it is overheating. The same cannot be said for a regulator that you can touch for several seconds or even more than a minute before it begins to burn your skin.
For the most part, any temperatures over 60 degrees C are a problem because that is more than enough to cause first degree burns.
What Causes a Voltage Regulator to Overheat?
A voltage regulator dissipates heat whenever it steps the voltage down. Therefore, the amount of heat the regulator produces is proportional to the amount of voltage it is expected to drop.
To understand why regulators overheat, you must take into account the input voltage, the output voltage, and the current passing through the circuit. According to Learning About Electronics, and as was mentioned before, a voltage regulator will take a higher input voltage and lower it to produce the output voltage that a particular electronic device can use.
The higher the input voltage, the greater the voltage the regulator has to drop, the more heat the regulator will produce. Don’t forget that the voltage the regulator drops becomes the heat that it eventually dissipates.
As such, the bigger the difference between the input and output voltage, the greater the heat. If your regulator is overheating, you can assume that the input voltage is simply too high.
Overheating can destroy your voltage regulator. I believe that there are ways to cool overheating regulators. However, if the regulator in question is dropping too much power and it is generating more heat than it can eject, I’m convinced that the regulator will overheat all the same, even if you have an efficient cooling system.
In that same vein, overheating is less likely to occur if the difference between the input voltage and output voltage is just 3 volts or less. With such a small difference, the regulator doesn’t have nearly as much power to dissipate, so it won’t overheat.
How Hot Does a Voltage Regulator Get?
The amount of heat a voltage regulator produces is proportional to the difference between the input and output voltage.
To identify the best means of cooling the regulator, you must first figure out how much power the regulator will dissipate.
This will eventually tell you how high the temperature will rise above the ambient air temperature. You can use this information to find a suitable cooling system.
Start by determining the input power and the output power.
You find the input power by multiplying the supply voltage with the current. You can also find the output power by multiplying the regulator’s output voltage and the current. Once you subtract the input power from the output power, you will get the power dissipated by the regulator.
At this point, it becomes a simple matter of adding the case thermal resistance to the Heatsink thermal resistance and multiplying the result by the power dissipated. Digikey has an example that makes these calculations easier to follow. The amount of heat a regulator can generate will vary with each regulator.
How Do You Keep a Regulator Cool?
If your regulator is overheating, is there a way to keep it cool? You have a few options at your disposal, including:
1). Change Regulators
Some regulators have ratings that are not compatible with your system. Rather than looking for a way to cool your regulator, you should consider getting a more efficient model that will step the voltage down without overheating.
2). Use a Heat Sink
If your situation won’t permit you to change regulators, you can keep a hot regulator cool by attaching a heat sink. Heat sinks are available in all kinds of shapes, sizes, and formats. But most of them follow the same principle.
They pull heat away from the section of the regulator that is overheating. Many heat sinks are just pieces of metal that you attach to the relevant component. The surface area matters. The larger it is, the more efficient the heat sink will be.
This is why some heat sinks have special features such as fins that were seemingly added for aesthetic purposes but which actually increase the sink’s efficiency by exposing more of the heat the regulator is producing to the air.
Depending on the amount of heat your regulator is producing, I think that it is a good idea to use thermal tape. The compound enhances the transfer of heat between the sink and the regulator. Naturally, the compound sits between these two objects.
3). Reduce the Input Voltage
Because a large difference between the input and output voltage produces a lot more heat, you can prevent a regulator from overheating by reducing the voltage you apply to the input. This is the most obvious solution
However, it isn’t always possible, especially in situations where the voltage requirements are fixed. This is why most people make do with a heat sink.
A fan isn’t the most efficient cooling tool. However, it can work in emergency situations until you find a better solution. Some people use cooling fans to support the work of a heat sink.
Are voltage regulators supposed to get hot? Yes, they are. This happens because the regulator is designed to step a higher voltage down to a lower voltage to suit the rating of a particular electronic device.
When the regulator steps the voltage down, the process creates heat which the regulator attempts to dissipate. The bigger the difference between the input and output voltage, the more heat the regulator generates.
If the input voltage is so much higher than the output voltage, the regulator will generate more heat than it can dissipate and it will overheat. Some regulators shut down when they overheat. But others keep working. This can damage them in the long run.
You have to look at a regulator’s datasheet to determine the appropriate temperature range within which it can operate. If the regulator exceeds this range, you can take action. You should also take action in situations where the regulator is too hot for you to handle it.