• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Electrical Engineering News and Products

Electronics Engineering Resources, Articles, Forums, Tear Down Videos and Technical Electronics How-To's

  • Products / Components
    • Analog ICs
    • Connectors
    • Microcontrollers
    • Power Electronics
    • Sensors
    • Test and Measurement
    • Wire / Cable
  • Applications
    • Automotive/Transportation
    • Industrial
    • IoT
    • Medical
    • Telecommunications
    • Wearables
    • Wireless
  • Resources
    • DesignFast
    • Digital Issues
    • Engineering Week
    • Oscilloscope Product Finder
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Women in Engineering
  • Videos
    • Teschler’s Teardown Videos
    • EE Videos and Interviews
  • Learning Center
    • EE Classrooms
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
    • FAQs
    • Ebooks / Tech Tips
  • EE Forums
    • EDABoard.com
    • Electro-Tech-Online.com
  • 5G

Testing considerations for USB and USB-PD

April 12, 2021 By Jeff Shepard

Designers integrating USB Type C and USB4 into their products confront several challenges to ensure interoperability and compliance. Compared with previous generations, the latest USB specifications are more demanding due to higher power and more complex power profiles, higher data transmission speeds, and more functionality in general. To address these challenges, test engineers must start with accurate and standard-compliant test instrumentation, software, and fixtures.

USB Type C power delivery (USB PD) is more complex, including 5 specifications ranging from 10W to 100W. The latest USB PD specification includes variable power scenarios, bidirectional power, and ALT mode for devices that are not compliant with USB PD powering protocols. USB hosts, devices, and accessories negotiate power delivery capabilities via the USB PD communications protocol that is executed on the new configuration channels (CC1 and CC2). The CC1 / CC2 line signals need to be verified for correct protocol transmission for dynamically changing power and managing ALT modes.

USB power profiles now include 5 specifications ranging from 10W to 100W. (Image: Rohde & Schwarz)

The latest USB PD specification v3.0 supports the higher and dynamically variable power. It is implemented by initially increasing the VBUS voltage while maintaining a current of 3A. The discrete voltage levels supported are 5V, 9V, 15V, and 20V. After reaching the maximum voltage of 20 V, the current can be increased up to 5A. For a given power level, a source must support all previous voltages and power levels. A 60W source meeting the new USB PD profile (PDP) specification must be able to supply 20V, 15V, 9V, and 5V, all with 3A of current. This requirement is intended to ensure that a higher wattage power source, for example, a laptop charger, can also support lower wattage (and lower voltage) devices such as a mobile phone handset.

Example of a 60W USB PD profile (power rails and maximum current) (Image: USB Implementers Forum)

The complexities of the latest USB PDPs require that designers spend more time dealing with performance verification and testing to ensure compliance. Additional challenges relate to maintaining backward compatibility with previous generations of USB power specifications.

Full-featured USB Type C adapters and cables are electronically marked (e-mark) and include an identification function chip that is accessible through the CC interface. Testing the e-mark functionality is now part of the USB Implementers Forum (USB-IF) USB PD compliance test specification.

USB PD 3.0 Fast Role Swap testing

USB PD 3.0 fast role swap (FRS) is designed to reduce the risk of data loss for USB peripherals due to an unexpected removal of a dock or hub power cable. It keeps devices powered, even if the dock or hub they are connected to loses power. Implementing FRS requires a precise and rapid exchange of messages between the dock/hub and the device being powered. FRS supports power delivery role swapping within 150μs. USB PD 3.0 chipsets and devices that support FRS are required to pass specific compliance testing. FRS tests are only required for dual-role power (DRP) ports. A DRP port can function as a power source or sink and may alternate between those states.

When a DRP initially operates as a source, the port takes the data-role of a downstream-facing port (DFP) and sends data downstream; it is often the port on a dock or a hub to which devices connect. On the other hand, when a DRP initially operates as a sink, the port takes the data role of an upstream-facing port (UFP), which connects to a hub or DFP of a hub and receives the data on a device or hub. Implementation of FRS enables the ports to change between DPF and UFP roles dynamically.

FRS compliance test instrumentation systems simulate a “power loss event” for the device under test (DUT) to initiate the FRS sequence. The test system continuously monitors the flow of power through VBUS and captures the message timing and power sequencing to ensure they meet the FRS requirements. There are specific test instrumentation and fixtures available for FRS compliance testing.

Biphase Mark Code PHY Integrity testing

The USB PD protocol uses biphase mark code (BMC) encoding on the CC communications interface to exchange the power profiles between two USB Type-C interfaces. Confirmation of the specified power negotiation on the CC link of a USB Type-C interface at frequencies of 270 kbps and 330 kbps and verification of the quality of the power supply on VBUS is another aspect of USB PD compliance testing.

Communication of the BMC signal specified in the USB PD standard is necessary to guarantee interoperability between USB components and devices and avoid any damage due to overvoltage and current. BMC PHY signaling is tested using compliance masks. Separate mask profiles are used to evaluate the modulated signal sequences of logic “one” and “zero”.

An eye diagram provides instant visual data to validate the signal integrity on the USB CC communications interface. (Image: Keysight Technologies)

Each manufacturer needs to apply to the USB Implementers Forum to get XIDs for its products. The initiator reads its responders’ XIDs along with other electronic certification data during the USB Type-C Authentication process. An external database (white list) that includes each XID and its related compliance test status is part of the compliance infrastructure. The initiator checks the white lists to confirm that the responder’s XID is listed after being authenticated. If the XID is on the white list, the initiator can be confident that the responder has passed compliance testing.

As a result of the 40 Gbit/s speed of USB4 (and Thunderbolt 3 & 4), measurement system noise and jitter cannot be ignored. The electrical tests for USB4 emphasize the Tf/Tf and intrinsic jitter performance of the test signal source. The test is performed by calibrating the test signal using the minimum input performance defined by the receiver standards to guarantee accurate receiver sensitivity measurement.

USB testing software

Software suites are available that support USB PD electrical and protocol compliance testing to validate and debug USB power delivery provider, consumer, dual-role device, and eMaker cable. For example, automation of the bit error rate testing (BERT) can minimize the effort needed for signal calibration and maximize test reproducibility. Various USB PD electrical and protocol compliance software suites offer several features that can speed design validation:

  • Conformance to the latest USB-IF USB PD specification and testing requirements
  • Performance of the BMC-PHY electrical, physical layer tests
  • Performance of the BMC-PROT protocol layer tests
  • Performance of the BMC-POW power state tests
  • Full automation of all tests needed for USB PD certification
  • Support for all types of USB PD device tests, including provider, consumer, dual-role device, and the eMarker cable.
  • Automatic saving of all waveforms, making them available for subsequent analysis and debugging
  • Supports automation of the USB PD compliance test process, including product registration and certification approval

Automated USB PD compliance software can enable designers and test engineers to perform all needed compliance testing and debugging in real-time and reduce product development times.

Summary

As shown, designers integrating USB Type C and USB4 into their products confront several challenges to ensure interoperability and compliance. Compared with previous generations, the latest USB specifications are more demanding due to higher power and more complex power profiles, higher data transmission speeds, and more functionality in general. To address these challenges, test engineers must start with accurate and standard-compliant test instrumentation, software, and fixtures.

References

How to Test USB Power Delivery Over Type-C, Keysight Technologies
PD 3.0 ‘Fast Role Swap” Compliance Tests, Teledyne Lecroy
Power Delivery Tests, USB Implementers Forum
USB Power Delivery Electrical and Protocol Compliance Test Software, Keysight Technologies

You may also like:


  • USB proliferation of capabilities and compatibilities

  • How to test USB4 designs

  • Overcoming the challenges of USB PD 3.0’s Fast Role Swap

  • Evaluating options for USB Type-C connections

  • Measuring the Universal Serial Bus (USB)
DesignFast Banner version: 22ccae6e

Filed Under: FAQ, Featured, Power Electronic Tips Tagged With: FAQ

Primary Sidebar

EE Training Center Classrooms

EE Classrooms

Featured Resources

  • EE World Online Learning Center
  • CUI Devices – CUI Insights Blog
  • EE Classroom: Power Delivery
  • EE Classroom: Building Automation
  • EE Classroom: Aerospace & Defense
  • EE Classroom: Grid Infrastructure
Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

R&D World Podcasts

R&D 100 Episode 7
See More >

Current Digital Issue

April 2022 Special Edition: Internet of Things Handbook

How to turn off a smart meter the hard way Potential cyber attacks have a lot of people worried thanks to the recent conflict in Ukraine. So it might be appropriate to review what happened when cybersecurity fi rm FireEye’s Mandiant team demonstrated how to infiltrate the network of a North American utility. During this…

Digital Edition Back Issues

Sponsored Content

Positioning in 5G NR – A look at the technology and related test aspects

Radar, NFC, UV Sensors, and Weather Kits are Some of the New RAKwireless Products for IoT

5G Connectors: Enabling the global 5G vision

Control EMI with I-PEX ZenShield™ Connectors

Speed-up time-to-tapeout with the Aprisa digital place-and-route system and Solido Characterization Suite

Siemens Analogue IC Design Simulation Flow

More Sponsored Content >>

RSS Current EDABoard.com discussions

  • Inductor core loss calculator is wrong?
  • Why are inductor recommended pads so small?
  • Temperature sensor readout
  • How to declare a non input use in vhdl?
  • Why is Analog Design so Hard????

RSS Current Electro-Tech-Online.com Discussions

  • Dog Scarer
  • Adding Current Limit Feature to a Buck Converter
  • software PWM
  • Opamp ciruit
  • Audio equalizer

Oscilloscopes Product Finder

Footer

EE World Online

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • Electro-Tech-Online Forums
  • Engineer's Garage
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • Wire & Cable Tips

EE WORLD ONLINE

  • Subscribe to our newsletter
  • Lee's teardown videos
  • Advertise with us
  • Contact us
  • About Us
Follow us on TwitterAdd us on FacebookConnect with us on LinkedIn Follow us on YouTube Add us on Instagram

Copyright © 2022 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy