You don’t need it though. The power regulation is a decision between the load and the supply devices, the cable is an unnecessary third party. The cable should just be a multicore connection between two things, not a third device.
If I had to go out on a limb though, I’d say it’s because manufacturers were selling cheap cables that didn’t meet the specification, and people were using them with higher power devices, causing overheating. By including a chip in the spec for the cable, you can push some of the responsibility back towards the cable manufacturer, and they can limit the maximum current to whatever they’ve designed to. In which case, we already do have different cables for different voltages - if your cable isn’t rated for 100W, then it might force a lower power even if your device and charger can do 100W. However it would be better if cable manufacturers would just meet the basic design specification to begin with, rather than creating unnecessary overhead.
hcbxzz@lemmy.world 1 year ago
You can do cable detection with just a few resistors. Why make everyone use active cables just for basic functionality? Aside from exceptional rare circumstances, cables should be passive devices IMO.
anotherandrew@lemmy.mixdown.ca 1 year ago
They don’t use cable ICs for basic power use. The IC in the cable (different ICs for different capabilities) is used for high power negotiation (ie the cheap thin cable won’t be able to do 100W, and the lack of chip ensures this safety requirement) and also for active equalization do you can get 40Gbps.
It’s a good thing, and cheap cables don’t need it at all. The system falls back safely.
hcbxzz@lemmy.world 1 year ago
Pull up resistors have solved the same problem much more simply for decades. Even with ICs, manufacturers can still make weak cables that lie about their capacity then burst into flames. If all else fails, the host can still directly measure cable resistance with some help from the client. The IC is not what making the cable safe, it’s the manufacturer.
anotherandrew@lemmy.mixdown.ca 1 year ago
I mentioned this in another post, but yes, resistor dividers are useful and have been used for ages. However things like component aging/damage and simply having enough headroom between different options limits the number of discrete states you can convey with a resistor divider.
I’m usually not a fan of overcomplicated solutions, but these identity chips aren’t that.