Min Power for Max Data Transfer for USB 3.2 Gen 2x2 (20 Gbps) etc ? - Page 1
Forum section: electronics / projects

author: Petdevils
author_rank: Newbie
timestamp: January 15, 2024, 06:13:30 pm
content: HelloI'd like to know the minimum power specs to look for in a USB-C and/or USB-A cables to ensure the Full/ Maximum Data Transfer for USB 3.2 Gen 2x2 (20 Gbps) ?​For example, Amperage, Wattage, Voltage in/out etc?This is for use with PC, Smart TV, External Drives, and other Android devices.We all know a lot of sellers are misleading with the weaselly way they describe capabilities of tech for sale...I'm worried I might buy a cable listed as "Up to - USB 3.2 Gen 2x2 (20 Gbps) speeds," and yet it might not get up to that full speed at all because the power for the cable wasn't quite enough ?You know, like in a similar way to how they advertise home solar panel systems packages where they have either one of - the power distribution system, or the solar panels - as being far underpowered/less capable than the other item. So they advertise the package with the biggest, most powerful sounding number... and yet people don't understand that that's not what they'll actually get because one item is vastly limited.That's the kind of thing I'm wary of happening.Maybe this doesn't work this way just with cables, I don't know?If anyone can find a list of min power levels for max speed for all the various levels of USB eg... USB 3.2 Gen 2x2, USB 3.2 Gen 2, USB 3.2 Gen 1 etc and so on and so on... that would be very useful. Then I can buy the best value min/max power spec cable for max speed tailored to the max speeds of each of my various devices (which are all different USB types).That way, I could save a bit of money but still get the best cables for the job (rather than just buying loads of highest spec cables even tho they won't all be capable of using all that speed).Other than that... I assume the only way to try to ensure a cable is even capable of the full speed of your max usb type (in your pc etc), is if they simply list that specific usb type on the item sale page?E.g. if the ad lists... "for USB 3.2 Gen 2x2" or "up to 20 Gbps" ?Any info would be greatly appreciated?Thank you for your help

author: wasedadoc
author_rank: Super Contributor
timestamp: January 15, 2024, 06:15:11 pm
content: Power has little if anything to do with USB speed.

author: IanB
author_rank: Super Contributor
timestamp: January 15, 2024, 06:17:37 pm
content: Speed is for data, power is for charging. They are two separate things.The best way to achieve expected transfer speeds is to buy only good quality cables from reputable sources. You may not have Apple devices, but Apple branded cables will usually meet their specs. Other brands also, but in general you get what you pay for.

author: wasedadoc
author_rank: Super Contributor
timestamp: January 15, 2024, 06:24:13 pm
content: Quote from: IanB on January 15, 2024, 06:17:37 pmAs with anything you buy you rarely get more than you pay for but not so rarely get less.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 15, 2024, 09:34:15 pm
content: Thunderbolt 3 cables all support 20 Gb/s and 100 W power deliver when used as USB cables. That's probable the easiest way to be sure.edit: typo GB/s -> Gb/s

author: ejeffrey
author_rank: Super Contributor
timestamp: January 15, 2024, 09:39:39 pm
content: Also, no USB type A cable supports USB 3.2 2x2. USB type A connectors only have a single pair in each direction, 2x2 operation requires two lanes per direction. The corollary of this is that any cable with a type A connector that advertised 2x2 is lying, and so anything else written there is suspect.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 17, 2024, 10:42:48 pm
content: Quote from: ejeffrey on January 15, 2024, 09:34:15 pmThat's 20 Gb/s, not 20 GB/s.... Comms is (always?) specified as bits per second, not bytes - the byte rate is usually variable due to bitstuffing or other low level encoding issues, such as being DC-free and having a recoverable clock.

author: magic
author_rank: Super Contributor
timestamp: January 18, 2024, 07:04:33 am
content: PCI and PCI-X buses, IDE disks were rated in MB/s