You need that for power regulation. One of the reasons that you can use a USB-C lead with anything is because all of the devices that require different power will just tell the cable that and the chip inside the cable deals with it. Otherwise there would have to be different cables for different voltage requirements.
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, consumer grade cables should be passive devices IMO.
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.
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. The IC is not what making the cable safe, it’s the manufacturer. And if all else fails, the host can still directly measure cable resistance with some help from the client.
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.
It doesn’t make any difference either it’s between the supply and the device or it’s between the cable and the device it’s still two devices.
By pushing the responsibility onto the cable it allows you to operate the cable directly from a USB port. So you can have things like electrical sockets with USB connections and you don’t have to have chips in the sockets, because typically they’re just dumb electrical interfaces. It also means that the device delivering the power doesn’t have to be actually fully switched on, so you can recharge your phone from a USB port on your computer and you don’t have to power the computer on. As long as there is an open electrical channel to the port the cable will deal with it all itself.
Also it’s more efficient because you would have to have a control circuit in every single power delivery device, but this way you can have it in just the one cable, so now it is one chip for an unlimited number of power delivery devices.
The cable has to carry the negotiated power safely. It’s not unnecessary, it’s absolutely critical. I’ve personally seen and diagnosed the result of when this fails.
For your low power applications there is no need and the spec allows for that.
How do you have the cable correctly identify itself if you don’t put some smarts in it? Or are you saying we should only be able to buy expensive cables fully rated for 100W (or higher as the spec has been updated) — and how do you prevent an older cable rated for 100W from being abused in a newer 200W circuit?
Divider resistors are okay, but the IC is a better choice for future proofing and reliability.
You need that for power regulation. One of the reasons that you can use a USB-C lead with anything is because all of the devices that require different power will just tell the cable that and the chip inside the cable deals with it. Otherwise there would have to be different cables for different voltage requirements.
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, consumer grade cables should be passive devices IMO.
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.
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. The IC is not what making the cable safe, it’s the manufacturer. And if all else fails, the host can still directly measure cable resistance with some help from the client.
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.
Removed by mod
It doesn’t make any difference either it’s between the supply and the device or it’s between the cable and the device it’s still two devices.
By pushing the responsibility onto the cable it allows you to operate the cable directly from a USB port. So you can have things like electrical sockets with USB connections and you don’t have to have chips in the sockets, because typically they’re just dumb electrical interfaces. It also means that the device delivering the power doesn’t have to be actually fully switched on, so you can recharge your phone from a USB port on your computer and you don’t have to power the computer on. As long as there is an open electrical channel to the port the cable will deal with it all itself.
Also it’s more efficient because you would have to have a control circuit in every single power delivery device, but this way you can have it in just the one cable, so now it is one chip for an unlimited number of power delivery devices.
Removed by mod
The cable has to carry the negotiated power safely. It’s not unnecessary, it’s absolutely critical. I’ve personally seen and diagnosed the result of when this fails.
For your low power applications there is no need and the spec allows for that.
Removed by mod
How do you have the cable correctly identify itself if you don’t put some smarts in it? Or are you saying we should only be able to buy expensive cables fully rated for 100W (or higher as the spec has been updated) — and how do you prevent an older cable rated for 100W from being abused in a newer 200W circuit?
Divider resistors are okay, but the IC is a better choice for future proofing and reliability.