Conformance and Interoperability

Protect your brand with proven USB-C® interoperability testing methods

In today’s world, USB-C® is fast becoming the universal standard. Consumer demand for quality is a key market driver, proven testing methodologies are vital, and compliance is non-negotiable. Whether you’re building consumer electronics, automotive systems or industrial hardware, interoperability testing is vital to delivering a reliable, frustration-free user experience. USB interoperability testing is a critical step in delivering a reliable, compliant and competitive product. 

Why USB interoperability testing matters for manufacturers 

With USB-C® now the mandated standard across the EU, and one that’s increasingly being adopted worldwide, manufacturers face growing pressure to ensure their devices work flawlessly across a wide range of hosts, devices, cables and operating systems. 

What USB interoperability testing means for your product 

Interoperability testing goes beyond checking whether your device meets USB specifications. It answers the real-world question: Will your product perform reliably across the diverse ecosystem of USB devices, cables and platforms your customers use every day? 

This involves testing your device with over 300 certified and non-certified USB hosts, hubs and accessories, across USB 2.0, USB 3.2, and USB Power Delivery (PD) profiles. It’s about identifying edge cases, compatibility gaps and performance issues before they reach your customers. 

Why manufacturers can’t afford to skip USB testing  

A device that charges slowly, disconnects intermittently or fails to initialise with certain hosts can lead to negative reviews, product returns and brand damage. In regulated markets, it can also mean non-compliance. 

With the EU’s Common Charger Directive now in force, USB Type-C® and USB PD are mandatory for many device categories. That raises the stakes for manufacturers, especially those targeting European markets. 

What should be included in your USB interoperability test plan?

A comprehensive test plan should cover:
  • Device-to-device compatibility

    Test across 300+ USB source/sink/data devices, including certified and non-certified products. 

  • Operating system behaviour

    Validate enumeration, driver loading and power negotiation across Windows, macOS, Linux and Android. 

  • Cable and connector impact

    Assess how passive, active and EPR-rated cables affect charging current, signal integrity and data throughput. 

  • Charging performance

    Evaluate charging speed, fallback behaviour and thermal performance across USB BC 1.2, USB PD 3.2, and proprietary fast-charging protocols like Quick Charge and Apple 2.4A. 

  • Alternate mode support

    Verify DisplayPort, HDMI and Thunderbolt functionality over USB-C, including signal switching and display output stability. 

  • Stress and edge cases

    Simulate ‘hot-plugging’ under load, low battery states, EMI/EMC interference and connector fatigue. 

How USB interoperability testing is performed 

Testing is conducted using a modular testbed equipped with programmable power supplies, USB protocol analysers and automated switching matrices. Each test is performed undercontrolled conditions, with detailed logs recorded for voltage/current behaviour, enumeration timing and error states.  

To pass, your device must:

initiate and sustain charging without interruption  

  • correctly enumerate across all tested hosts 
  • maintain data integrity under continuous load 
  • recover smoothly from disconnects or power failures

Custom test scenarios can also be devised for specific use cases, such as automotive infotainment systems or industrial USB hubs. 

Real-world example: Compliance success through testing

A manufacturer preparing for the EU USB-C mandate submitted a family of devices for interoperability testing. The results revealed: 

  • inconsistent USB PD negotiation across SKUs 
  • EMI failures on one model 
  • DisplayPort instability with certain cables 

After remediation, the devices passed all USB-IF certification tests and were successfully submitted under the Qualification by Similarity (QbS) programme, saving time and avoiding costly redesigns. 

Final thoughts: Why manufacturers should invest in USB testing now 

USB interoperability testing isn’t just about ticking boxes; it’s about delivering a product that works reliably in the hands of your customers. With USB-C® and USB PD now the norm, the margin for error is shrinking. A robust test strategy is your best defence against compatibility issues, compliance failures and reputational risk. 

Ready to test your USB product?

Whether you’re launching a new device or preparing for EU compliance, we can help you build a test plan that ensures your product is robust, reliable and regulation ready. 

Why Resillion? 

When you choose Resillion for your USB conformance needs, you’re partnering with a team that combines deep technical expertise with real-world testing experience. Our state-of-the-art facilities and proven track record mean your products benefit from the most comprehensive and up-to-date testing protocols available.  
As part of our ongoing commitment to staying at the forefront of USB compliance andinnovation, our team will be attending the upcoming USB Compliance Workshop in Portland or USA. Events like these help us stay aligned with the latest specifications, tooling, and best practices, so we can help you get to market faster and with confidence.

We’re committed to proactive problem-solving and personalised support, guiding you through every stage of compliance—from initial planning to certification and beyond. With Resillion, you gain confidence that your devices not only meet regulatory requirements but stand out for their reliability and performance in the marketplace. 

Note: Resill!on is a USB-IF Authorized Independent Test Lab (ITL).