I have a NCP1117 5V voltage regulator that is on an Arudino Mega. The Arduino Mega, with all of the necessary electronics parts for the project, draws around 200mA when operational. When using a battery that has a maximum voltage of 12.6 Volts, the voltage regulator gets very hot but it works. (Case temperature of 96 degrees Celsius)
The goal of the project is to use a 4S LiPo battery which will have a maximum voltage of 16.8 Volts. This overheats the voltage regulator and it thermally shutdowns (This happens at 175 C according to the datasheet).
Is there a good way to cool these devices. It is a SOT-223 package on an Arduino Mega board. I have attached a small 5mmx5mm heat sink on the top, and it did help the temperature but not enough for the required 4S battery voltage. It also does not make the best contact due to the low surface area on the top of the device.
I don't like the idea of having a fan so is there a good way to passively cool this device? I was thinking of adding an additional heat sink on the bottom of the board underneath the voltage regulator. Just put it on the bottom solder mask. Is that just a dumb idea or is there a better way to cool these?