Version: 1.0.1
Last updated: 2024-02-01
Legend
| Product Verb | Development Action |
|---|---|
| "MUST" | Mandatory product requirement |
| "SHOULD" | Optional recommendation |
| "MAY" | Nice to have |
Requirements Scope
This specification document describes the criteria that ChromeOS Compatible passive USB cables meet. This specification should not be used for WWCB products, or a product designed and certified together with a Chromebook.
Passive cable types
This specification applies to USB cables with the following connector combinations:
- USB-A (male) to USB-C (male)
- USB-C (male) to USB-C (male)
- USB-A (female) to USB-C (male)
- micro-B (male) to USB-C (male)
Principles
ChromeOS Compatible USB cables:
- Work with any ChromeOS device out of the box
- Uphold a quality standard
- Comply with international standards and local regulations for safety and efficiency.
Required Technologies
Cables MUST be based on the following technologies:
- The USB cable MUST comply with the USB Type-C Specification R2.2 or later.
- If the cable supports better than USB2.0 speed or higher than 3-amp current, then it MUST comply with the USB Power Delivery R3.1 V1.7.
Prerequisite Certifications
- The cable SHOULD be USB-IF Certified and discoverable on the public portal page.
- If the cable reports Intel SVID, then the cable MAY be Intel approved with documentation. This applies only to USB4 Gen3 cables, Thunderbolt 3 cables, or Thunderbolt 4 cables.
Hardware and Visual Design Requirements
USB-IF Logos
- The USB cable SHOULD use USB-IF standardized power and data indication logos as indicated in their logo usage guidelines for cables.
USB-IF Certification
- The USB cable SHOULD be USB-IF Certified
- If an approved USB logo is used, then the cable MUST be USB-IF Certified
- The cable SHOULD be discoverable on public portal page
Thunderbolt Logos
- If the cable is certified for Thunderbolt 3 or Thunderbolt 4, then the cable MUST follow Intel guidelines for proper Thunderbolt logo usage.
USB Type-C Cable Requirements
Logos for USB-C to USB-C Cables
- All USB 3.2 Gen 1 USB-C to USB-C cable SHOULD bear the appropriate USB-IF logos for the performance of the cable.
- All USB 3.2 Gen 2 USB-C to USB-C cable SHOULD bear the appropriate USB-IF logos for the performance of the cable.
- All USB4 Gen 3 USB-C to USB-C cable SHOULD bear the appropriate USB-IF logos for the performance of the cable.
- All USB 2.0 USB-C to USB-C cables SHOULD bear a High-Speed USB Trident logo.
- Rationale: Inconsistent use of logos is likely to cause user confusion.
- The USB logo SHOULD indicate the cable's power capability.
- The USB cable SHOULD follow the guidelines for USB Performance logos (refer to https://www.usb.org/logo-license/).
Identification
USB-C to USB-C Cables
- USB-C to USB-C cables rated at 3A current and USB 2.0 performance only MAY
have an eMarker.
- All other kinds of USB-C to USB-C cables MUST contain an eMarker, with performance and current capability information properly identified.
- If eMarked:
- Cable eMarker MUST have vendor-specific VID and unique PID
- eMarker MUST support Ra weakening
- Ra weakening MUST correctly follow vRa-reattach after UnattachedWait.SRC
state
- Cables with Ra weakening that fail this may appear as a "fake Rd" on oscilloscope
- Unless cable contains feature requiring power, MUST be marked "Vconn
required = 0"
- Example: cable contains built-in lights, volt+ammeter display, etc. requiring Vconn
- If eMarker reports SVID Modes, they MUST be disclosed to WWCB.
- Proprietary functions and/or Firmware-update via Manufacturer. Mode, and their purpose, MUST be disclosed.
- Intel SVID (Thunderbolt) MUST be appropriate for application and Intel approved
- USB4 Gen3 cable MUST have Intel SVID for TBT3 backward compatibility
- USB4 Gen4 cable MUST have Intel SVID for TBT3 backward compatibility
Hardware Requirements
Specifications
- Cable plug dimensions MUST comply with USB-IF specifications.
- The cable SHOULD use USB-IF Certified components and connectors.
- If intended for data+video and "Full Featured":
- If <=0.8m, strongly recommended to be USB4 Gen3 (40gbps)
- If >0.8m and <=1m, strongly recommended to be USB3.2 Gen2 (20gbps) or USB4 Gen2 (20 gbps)
- If >1m and <=2m, strongly recommended to be USB3.2 Gen1 (5gbps)
- The above lengths are informative per Type-C R2.0 spec based on current
technological limits.
- See USB Type-C Specification Section 3.1.2, Table 3-1 USB Type-C Standard Cable Assemblies and Section 5.4, Table 5-1 Certified Cables Where USB4-compatible Operation is Expected for more details.
- Products exceeding these technological limitations are permitted if USB-IF
Certified.
- "The cable lengths listed in the table are informative and represents the practical length based on cable performance requirements."
USB Type-C Legacy Cable and Adapter Requirements
- USB-A (male) to USB-C (male)
- MUST have a single 56 KΩ pull-up resistor connecting Vbus and CC pin in the USB-C plug.
- Cable MUST either be rated for USB 2.0 or USB 3.2 Gen 1/2, having the appropriate number of data carrying wires
- If the cable is capable of USB 3.2 Gen 1/2, the USB-A plug MUST be the USB 3.1 USB Type-A plug with 9 pins.
- If the cable is only capable of USB 2.0, the USB-A plug MUST be the USB 2.0 USB Type-A plug with 4 pins.
- USB-A (female) to USB-C (male)
- MUST have a single 5.1 KΩ pull-down resistor connecting Gnd and CC pin in the USB-C plug.
- Adapter MUST be rated for USB 3.1 Gen 1.
- USB-A receptacle MUST be a USB 3.1 Standard-A Receptacle with 9 pins.
- micro-B (male) to USB-C (male)
- MUST have a single 5.1 KΩ pull-down resistor connecting Gnd and CC pin in the USB-C plug.
- Cable MUST either be rated for USB 2.0 or USB 3.2 Gen 1/2, having the appropriate number of data carrying wires
- If the cable is capable of USB 3.2 Gen 1/2, the Micro-B plug MUST be the USB 3.1 USB Micro-B plug with 10 pins.
- If the cable is only capable of USB 2.0, the Micro-B plug MUST be the USB 2.0 USB Micro-B plug with 5 pins.
Revision History
| Date | Version | Notes |
|---|---|---|
| 2024-02-01 | 1.0.1 | Republication on a new platform |
| 2023-10-11 | 1.0 | Initial Partner Site Publication |