3 ms·

USB-C cables are not all capable of carrying 60 Watts. They're supposed to, but there's no way to know that the cable you are holding, or looking at buying, is

by avhon1 5y ago

USB-C cables are not all capable of carrying 60 Watts. They're supposed to, but there's no way to know that the cable you are holding, or looking at buying, is actually capable of that. Back in 2016, Benson Leung tested many USB-C devices and cables. I went through his amazon profile [1] and found an example of an out-of-spec cable he tested[2]. > Furthermore, the DC Resistance of this cable is too high: > VBUS 140.82 mΩ > GND 90.09 mΩ > The IR drop on GND is too high. At 3A, the maximum allowed resistance is 83.3 mΩ, and this cable exceeds that. Furthermore, the seller also advertised that this cable was "100W" capable, meaning that the maximum is actually at 5A, with a maximum resistance of 50.0 mΩ. In both cases, this cable has too high IR drop. [1] https://www.amazon.com/gp/profile/amzn1.account.AFLICGQRF6BRJGH2RRD4VGMB47ZA https://www.amazon.com/gp/profile/amzn1.account.AFLICGQRF6BR... [2] https://www.amazon.com/gp/customer-reviews/R1Y953RCSLMFSU https://www.amazon.com/gp/customer-reviews/R1Y953RCSLMFSU

ksec 5y ago
I am not sure if 60W minimum is a PD requirement or USB 3.0 requirement. But I am 100% sure there are USB C Cable that only do USB 2.0 and doesn't do 60W charging.
- glennfle 5y ago
  I would love to find the citation outside of Wikipedia for the USB-C 60W requirement. Apple makes a USB-C charging cable that only does USB 2.0 but is capable of up to 100W. And you can find cables like this Belkin one that promise 15W: https://www.belkin.com/my/chargers/wall/usb-c-home-charger-usb-c-to-usb-c-cable-usb-type-c/p/p-f7u008/ https://www.belkin.com/my/chargers/wall/usb-c-home-charger-u... But perhaps it’s out of spec?
- chx 5y ago
  That is not an up to specs cable. Buy USB IF certified cables.
glennfle 5y ago
I just read through the USB-C spec, and the closest thing it says to 20V/3A minimum is in a chart that has a footnote: "the USB Type-C specification requires that a Source port that supports USB BC 1.2 be at a minimum capable of supplying 1.5 A and advertise USB Type-C Current @ 1.5 A in addition to supporting the USB BC 1.2 power provider termination." Is there a more explicitly states a minimum of 20V/3A? I may be misreading the table above this (Table 2-1). https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...
- glennfle 5y ago
  Nope, finally found it in the USB-C spec, section 4.6.2, covering cables: "USB Power Delivery in Standard Power Range (SPR) operation is intended to work over un- modified USB Type-C to USB Type-C cables, therefore any USB Type-C cable assembly that incorporates electrical components or electronics shall ensure that it tolerate, or be protected from, a VBUS voltage of 21 V." This comes after a table that would seem to indicate USB-C as a whole supports a minimum of 7.5W, but then this cable-specific section expands that. However, it notes that it must tolerate or be protected from, which in this context I gather means "must pass power through."

by avhon1 5y ago

ksec 5y ago

I am not sure if 60W minimum is a PD requirement or USB 3.0 requirement. But I am 100% sure there are USB C Cable that only do USB 2.0 and doesn't do 60W charging.

glennfle 5y ago
I would love to find the citation outside of Wikipedia for the USB-C 60W requirement. Apple makes a USB-C charging cable that only does USB 2.0 but is capable of up to 100W. And you can find cables like this Belkin one that promise 15W: https://www.belkin.com/my/chargers/wall/usb-c-home-charger-usb-c-to-usb-c-cable-usb-type-c/p/p-f7u008/ https://www.belkin.com/my/chargers/wall/usb-c-home-charger-u... But perhaps it’s out of spec?
chx 5y ago
That is not an up to specs cable. Buy USB IF certified cables.

glennfle 5y ago

I just read through the USB-C spec, and the closest thing it says to 20V/3A minimum is in a chart that has a footnote: "the USB Type-C specification requires that a Source port that supports USB BC 1.2 be at a minimum capable of supplying 1.5 A and advertise USB Type-C Current @ 1.5 A in addition to supporting the USB BC 1.2 power provider termination." Is there a more explicitly states a minimum of 20V/3A? I may be misreading the table above this (Table 2-1). https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%20R2.0%20-%20August%202019.pdf https://www.usb.org/sites/default/files/USB%20Type-C%20Spec%...

glennfle 5y ago
Nope, finally found it in the USB-C spec, section 4.6.2, covering cables: "USB Power Delivery in Standard Power Range (SPR) operation is intended to work over un- modified USB Type-C to USB Type-C cables, therefore any USB Type-C cable assembly that incorporates electrical components or electronics shall ensure that it tolerate, or be protected from, a VBUS voltage of 21 V." This comes after a table that would seem to indicate USB-C as a whole supports a minimum of 7.5W, but then this cable-specific section expands that. However, it notes that it must tolerate or be protected from, which in this context I gather means "must pass power through."