The ESP32/ESP32-S2/ESP32-S3 chips are very powerful for their size, and when running with the radio turned on, especially for long periods of time, they draw a low of current and get quite warm.
The TinyPICO, TinyS2 and TinyS3 boards are very small, and tightly packed in with components, so they don’t have a lot of surface area for heat to dissipate into the air.
There is nothing to be alarmed about though. Even when running hot, everything is well within spec, so long as you follow some simple rules:
- If you need to keep Wi-Fi active for long periods of time, like for a soft-ap setup, make sure you don’t enclose your board in a small case or a case that has no air flow, as the heat will build up with no place to escape to.
- If you need to put your board in a case, add a small fan to pull the hot air out to keep the ambient temperature around the board as low as possible. If a fan is not possible, try to at least have air vents to let heat out.
- Try to keep WiFi use short and sparse, if your project allows. Sleep/Deep sleep your board whenever you can, even when running off 5V as that will allow the ESP32 to cool down more than if it was fully awake.
- If you are using a battery in your project, don’t sit the board on the battery or sandwich them together, as the battery will also generate heat and will increase the temperature of the board.
For TinyPICO Nano and NanoS3 projects, please ensure you:
- Solder the thermal pad on the back to a GND pad on your carrier board – This is essential.
- Allow enough clear space on your carrier board for thermal transfer of heat.