A quotation for USB PD compliance usually arrives as a single figure, and a single figure is the hardest kind to compare. The programme behind it has four separate cost lines, and two of them are driven by decisions the brand makes before the test house is involved. Splitting the quotation into those lines is what turns a number into a plan.
USB PD certification: the four cost lines behind one report
Protocol and interoperability testing, safety and construction, EMC, and documentation with file maintenance.
Only the first line belongs to the USB programme itself; the other three come from the market the product is sold in. They are quoted together because they are usually run in parallel on the same samples, but they are driven by different decisions and they fail for different reasons.
Understanding the split matters because the cheapest way to reduce the total is not to negotiate the test house. It is to take the four decisions correctly before the samples are built: the profile set, the component list, the enclosure and the accessory.
Cost line 1: protocol and interoperability testing
This line is driven by how many profiles the product claims.
A charger that implements a single fixed profile is tested against that profile; a multi-port product that shares power across ports, supports an adjustable range and negotiates at several voltage tiers multiplies the test positions. Multi-port power sharing is the usual reason this line is larger than expected, because the sharing rules have to be exercised in each combination the product allows. Reducing the claimed behaviour to what the product actually needs is the cheapest saving available in the whole programme.
Cost line 2: safety and construction
Safety is a market requirement, not an optional extra attached to the protocol test.
The relevant standard for this product family is IEC 62368-1, and the work it generates depends on the construction: creepage and clearance, the isolation barrier, the thermal design and the fault conditions assessed. A design that has already been through a safety review costs less to test than one that meets the protocol requirement and has never been examined for construction. This is also the line that a component substitution can reopen, because the substitute has to be assessed against the construction that was qualified.
Cost line 3: EMC and the accessory
The charger and the adapter can be two products with two obligations.
Emissions and immunity are measured on the product and its input arrangement, and where the retail box contains a separate mains adapter, that adapter carries its own conformity. A brand that specifies the adapter late pays for a second test programme and a second documentation set, and it pays for them in series rather than in parallel, which is where the schedule cost comes from.
| Cost line | What it covers | Usually paid by | What drives it up |
|---|---|---|---|
| Protocol and interoperability | Profiles, power sharing, negotiation | The party claiming the capability | Multi-port behaviour and adjustable ranges |
| Safety and construction | Isolation, creepage, thermal, fault conditions | The responsible party on the marking | An untested construction or a late substitution |
| EMC and accessory | Emissions, immunity, adapter conformity | The brand selling the box | An adapter specified after the charger |
| Documentation | Technical file, declarations, marking | The brand | A revision change after the file is written |
Cost line 4: documentation, marking and file maintenance
Documentation is a cost line even when it produces no test result.
The technical file, the declaration, the label artwork and the instruction sheet have to describe the tested revision, and each of them has to be updated when that revision changes. Keeping the file current is one of the obligations attached to the responsible party, and a file that has drifted from the product is more expensive to fix during a review than to maintain while the programme runs.
What a re-test costs after a change
The price of a change follows the part that changed.
Artwork, marking or packaging changes update the documentation. A substitution in the power stage or the control circuit reopens the safety and protocol assessment, because the tested construction has moved. A change of enclosure reopens the thermal and safety review. A change of adapter adds a second product to the pack. Asking which of those four categories a proposed change falls into is the fastest way to price it before it is made.
Where money can be saved legitimately
Four savings that do not remove a control.
Claim only the profiles the product needs; freeze the adapter specification with the charger; use a platform whose construction has already been reviewed; and write the technical file against the revision that will ship rather than the revision in the prototype. None of those reduces what the product is tested against, and all of them reduce the number of test positions or the number of programmes that have to run twice.
FAQ
Is USB PD certification separate from safety certification?
Yes. The protocol and interoperability work belongs to the USB programme, while the safety, electromagnetic and market requirements come from the destination market. A product needs both, and they are usually run in parallel on the same samples. The protocol and interoperability work belongs to the USB programme while the safety and market requirements come from the destination, and both run on the same samples.
How much does a multi-port charger add to the test programme?
It adds test positions rather than a new programme. Every power-sharing combination the product allows has to be exercised, so the cost grows with the number of ports and the number of rules, which is why the claimed behaviour should match the product’s actual use case. It adds test positions rather than a new programme, because every power-sharing combination the product allows has to be exercised.
Can we reuse the factory’s reports for our brand?
Where the tested configuration matches what you ship, the evidence supports the product and the change is documentary. Where the enclosure, the components or the accessory differ, the difference is assessed, and the assessment determines whether testing is needed. Where the tested configuration matches what you ship the evidence supports the product and the change is documentary, and where the enclosure or accessory differs it is assessed.
What is the most common cause of an unexpected re-test?
A late component substitution or an adapter specification that changed after the charger was tested. Both move the product away from the tested construction, and both are cheaper to prevent by freezing the bill of materials than to correct afterwards. A late component substitution or an adapter specification that changed after testing moves the product away from the tested construction, and freezing the bill of materials prevents it.
How should two quotations be compared?
Line by line against the four cost lines, with the claimed profiles, the adapter arrangement and the documentation deliverable stated in each. Two totals that cover different scopes cannot be compared, and the difference usually sits in the documentation line. Compare line by line against the four cost lines with the claimed profiles, the adapter arrangement and the documentation deliverable stated in each.
Next step
Send the port configuration, the claimed profiles, the adapter arrangement and the markets to Wecent Group through the contact page. The reply separates the protocol, safety, EMC and documentation lines for that configuration and states what a later change would reopen. Related reading: OEM and ODM charger manufacturing, GaN charger applications and our charger factory. External references: USB Power Delivery specification, USB-IF compliance programme, IEC standards, EU Low Voltage Directive, UL standards and certification and TUV testing services.
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