would you pls explain the Apalis TK1 operature temperature defination? we check the datasheet show the range between -25 ~85 Celsius degree.
can we understand it is ambient temperature instead of Soc case temperature?
what is the configuration of your temperature cabinet to test the Apalis TK1?
Normally, we support the operation temperature is ambient temperature. the customer test their device which has a customized heatsink to pass the 60 Celsius ambinet temperature testing.
Additional Note: If you want to go up to the upper temperature limit you need to have a good cooling solution (e.g. passive heatsink, heatsink with fan, heatspreader to attach to a case, etc). The CPU will throttle down if it gets too warm and even stop before overheating which is of course more likely when operating at high ambient temperatures.
Our system will (have to) operate in ambient temperature from -40C to + 75C and we are looking at Apalis TK1 (ticks all the boxes but the temperature range!). The upper limit of +85C will not a problem when a cooling solution is present. But what about the lower temperature limit? What is the limiting factor of the unit down to -40C? As stated in the data sheet, the storage temperature can go down to -40C (Flash is limiting factor). Will the SoC not start?
Will a “heating solution” be an option? To heat the box and wait until the ambient temperature is above -25C?
Our system will (have to) operate in ambient temperature from -40C to + 75C and we are looking at Apalis TK1 (ticks all the boxes but the temperature range!). The upper limit of +85C will not a problem when a cooling solution is present. But what about the lower temperature limit?
Yes, what about it? Will it just not boot or explode? Well, the SoC is just not rated to be used below -25 deg C by NVIDIA. Why exactly we do not know, don’t want to know and also never ever tried.
What is the limiting factor of the unit down to -40C?
Definitely the SoC but maybe evan alos RAM and/or flash.
As stated in the data sheet, the storage temperature can go down to -40C (Flash is limiting factor). Will the SoC not start?
Probably. Plus you void your warranty.
Will a “heating solution” be an option? To heat the box and wait until the ambient temperature is above -25C?
I guess that should work.
Thanks in advance, Johan
You are very welcome. I also asked our hardware engineers for further comments as I am just a humble software manager.
I was asked to help from the hardware side. Let me first explain the upper temperature limit. We specify 85°C ambient temperature. However, for the TK1, the maximum junction temperature of 105°C is more important. Whatever you do, make sure your cooling solution keeps the die below 105°C. There is an on board temperature sensor which monitors the temperature and starts throttling the CPU if the temperature reaches a certain level and will do an emergency shut down if the 105°C are exceeded. According to our tests in the temperature chamber shows that our Apalis heat sink with a mounted fan has thermal resistance of around 3°C/W. This means when you run it with 75°C environment temperature, you get a maximum temperature difference between environment and junction of 30°C. This means with our standard cooling solution, you could dissipate around 10W. Which is almost at full load.
Now to the lower limit. This limit is officially -25°C. I just noticed that there is a typo in our datasheet. In our datasheet we state minimum junction temperature of 0°C. I checked it again with the SoC datasheet. The junction temperature range is -25° to 105°C. We will correct it in the next revision of our datasheet.
There are actually two components on the module which limit the lower temperature, the SoC and the eMMC. Both devices are officially rated for -25°C. This does not mean they are not working below that, but it is not guaranteed. The most difficult part at low temperature is starting the system. As soon as the system is started, the self heating reduced potential issues. Let us assume again that we are using our standard heat sink and dissipate 10W. This means the die temperature of the SoC is actually 30°C higher than the environment. This could be further optimized by turning off the fan at low temperatures.
Unfortunately, we cannot guarantee that the module works below the specified -25°C. However, if you need to be able to reliable boot your device at such low temperatures, there could be two solutions. The first one is adding a heating system. The second one is using an external watchdog supervisor. If the module is not able to boot since it is too cold, the watchdog will notice it and reboot it again. Assuming that the module heated itself up while trying to boot for the first time, the chances are high that it boots the second time.
