Do 5v regulators always get hot?

Answer 1

There are several factors that affect the heat output of a voltage regulator. A linear regulator such as a 7805 series will pass the same amount of current as the load draws. The regulator will also have a certain voltage across it and can be calculated by subtracting the output voltage (5V in this case) from the source voltage. The source voltage might be anywhere from 7 volts up to as much as 30 volts.

The heat generated in the regulator can be calculated using the power equation, power = current x voltage. As stated above, the current is dependant on the load. As the current increases, so the power dissipated in the regulator increases. Similarly, as the source voltage increases, so does the power dissipated by the regulator.

The regulator will always show a temperature rise but how hot it gets depends on how effectively the heat is drawn away from the regulator. If the regulator is mounted on an effective heat sink, it can dissipate large amounts of heat without becoming hot. Without a heatsink, the same regulator in the same situation will become far hotter.

All regulators have certain limits for power dissipation and temperature. The data sheet will have information on the limits and they should always be noted during a design phase.