I can totally see this happening but 'low power' is also relative. When Canon designed the Digic X with its design power (I'd estimate it somewhere around 5W based on power consumption), they must have realized very early on that thermals will be challenging. In this case, engineers tend to put more sensors in the package and make sure that software engineers can implement their thermal models to track temperature as well as possible.It is indeed basically free to add one into the silicon, but you have to know what you're doing and actually talk to the software people. During my time at a silicon vendor we had multiple SoCs that had sensors on silicon. But all mention of that was scrubbed from datasheets and software, since a lot of mistakes were made:
And more. This was because at design time there was no requirement for a temperature sensor. These SoCs were considered 'low power', so thermal management wasn't strictly needed.
- putting it in the 'wrong' place on the die, next to a coprocessor that consumes a lot of power
- playing with the sensor design so readings between different revisions don't match
- forgetting to document the gates that disable it by default
Someone else suggested that "3" may refer to the discrete sensors. I could believe that they have 3 discrete sensors in addition to anywhere between 2-10+ integrated ones...Also, there's a big difference between these 2 sentences:
I don't think we can be certain that there are only 3 sensors in the camera, just that Canon UK told Gordon that 3 are being used. And I suspect a lot of details are getting lost in the chain from Canon.jp engineer → Canon.jp marketing → Canon.uk marketing → Gordon.
- "There are 3 sensors, which we use in the algorithm"
- "There are 3 sensors which we use in the algorithm"