I’m working on a personal project that requires 6 Play Station Eye Cameras (if you think that sounds excessive, that’s because it totally is.) And when powering 6 USB cameras, you want to ensure you don’t exceed the maximum USB current draw of your computer. So I looked up the datasheet for the Play Station Eye, and found that the maximum current draw for a single camera is 500mA.
However, upon mentioning this to one of our mentors, he suggested that that spec could very well be an overly conservative estimate, as 500mA is also the maximum current limit of most USB ports. And sure enough, upon measuring the current using my handy dandy USB power measuring thingy, the actual current draw from one of these cameras when capturing video never goes above 120mA.
Granted, there is a microphone array on these cameras that I’m not using, which could increase the current draw past what is seen here. However, I kind of doubt that the microphone array draws 380mA (I could be completely wrong though.)
Just something interesting I discovered while tinkering that I thought might be relevant to anyone using these cameras (or 6 of them for that matter )
So your data sheet isn’t wrong, it’s listing the USB Spec max of 500mA.*
That being said, it’s great to know the actual usage of the product you have in hand so you can plan for it. Measuring it was a good call and I’m glad you posted about it.
*Someone is going to come in and tell me that “USB can provide more than that!” and, yes, it can but beyond 500mA, it’s technically supposed to be negotiated in various ways. In reality, the USB spec is all over the place when it comes to implementations.
Correct, it isn’t wrong in that it does list the correct USB max current draw for a single port. But it is wrong in that the product itself doesn’t draw anywhere near that amount of current. Which is what I assume is meant when they define what the max current requirements for this product are.
Ehh? It’s a consumer product and I don’t think they were aiming for an engineer of any type to be hacking on it many years down the road.
It’s also a hard lesson to learn that you can’t always trust a datasheet. At least it didn’t cost you $50,000.
I’ll also note that it is marked as “Power Consumption” and, technically, if you shorted it somehow, it would draw a Max of 500mA from the USB port on a playstation because that’s what that port would supply.
What if I plugged it into a 5V 2A supply with a spliced USB connector? If it shorted out, it would draw more than 500ma. The number on the datasheet is conveniently the same as the 500ma USB port spec, but is not a relevant number (other than implying that the working current of the device is <= 500ma).
This is totally fair… however, I will again mention that the device in question was purpose built to be plugged into a PS3 - technically by you plugging it into something else that isn’t a PS3, you aren’t following the “spec sheet” that was posted above and came with the cameras.
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