For many years, 12V has been a natural choice for powering Customer Premises Equipment (CPE). It is familiar, widely supported and deeply embedded in existing hardware architectures.
But as the industry moves towards USB-C Power Delivery, there is a good reason to revisit that assumption.
Should 12V automatically remain the default for the next generation of CPE?
At NetBit, we believe 15V deserves serious consideration.
The 36W question
A common 36W CPE requirement illustrates the issue clearly.
At 12V:
12V × 3A = 36W
At 15V:
15V × 2.4A = 36W
The equipment receives exactly the same power, but the current requirement falls by 20%.
That difference matters.
At 12V, a 36W requirement already uses the full 3A capability of a standard USB-C cable path.
At 15V, the same 36W requires only 2.4A, leaving additional current headroom within the same 3A architecture.
For an OEM developing a new CPE platform, that raises a simple but important question:
If the same 36W can be delivered at 15V and 2.4A, why design around 12V and immediately operate at the 3A ceiling?
USB-C PD changes the design logic
There was nothing inherently wrong with choosing 12V for traditional CPE.
Historically, the power supply and powered device were typically designed as a dedicated pair. The input voltage was selected around the internal architecture of the equipment, and 12V became an established standard across broadband, networking and other CPE applications.
USB-C PD changes that environment.
Voltage, current, cable capability and power negotiation now form part of the complete system architecture.
There is also an important distinction between 12V and 15V within USB Power Delivery.
15V is one of the standard fixed USB-PD voltage levels. 12V is not.
12V can still be supported through an appropriate USB-PD implementation, but for a completely new CPE platform it is reasonable to ask whether retaining it remains the best approach when 15V already fits naturally within the fixed-voltage USB-PD architecture.
As discussed in our previous articles on USB-C PD power limitations in CPE and the challenges of retaining 12V within a USB-C PD architecture, these considerations become particularly important at common CPE power levels.
Lower current can create wider benefits
The argument for 15V goes beyond remaining below 3A.
For a given power requirement, increasing the voltage reduces the current required to deliver that power.
Moving from 3A to 2.4A represents a 20% reduction in current. Because resistive losses are proportional to current squared, the theoretical I²R loss at 2.4A is approximately 36% lower than at 3A, assuming the same resistance.
That does not mean a complete 15V CPE system will automatically be 36% more efficient.
Overall efficiency still depends on the PSU topology, cable, internal DC conversion, component selection and operating load.
What lower current can do is reduce resistive losses, voltage drop and thermal stress across the power path.
For equipment that may remain powered 24 hours a day and be deployed across hundreds of thousands or millions of homes, even small improvements in power architecture can become significant.
Think beyond the PSU
The wider power system also matters.
A CPE platform requiring 36W at 12V needs the full 3A available on a standard USB-C cable path. That leaves little current headroom and can influence decisions around PSU rating, cable specification and the wider PD implementation where additional operating margin or peak power may be required.
At 15V, the same 36W requirement needs only 2.4A.
That additional margin gives designers greater flexibility when specifying the complete power solution.
For high-volume CPE programmes, those decisions can have a meaningful effect on cost, efficiency, thermal performance and long-term reliability.
The objective should not simply be to select the lowest-cost PSU. It should be to design the most appropriate and efficient power architecture for the product as a whole.
This does not make 12V obsolete
There are many existing products where moving away from 12V would make little sense.
An established platform may already have a mature and proven 12V architecture. Changing the input voltage could require component changes, redesign, additional validation and certification work.
For those products, retaining 12V may remain entirely appropriate.
The argument is different for new hardware platforms entering the design phase today.
If a product is already being redesigned around USB-C PD, the input voltage should be treated as an engineering decision rather than a historical default.
Could 15V become the new default?
We believe it could.
At 36W, the comparison is difficult to ignore:
12V requires 3A.
15V requires 2.4A.
The same power is delivered at lower current, with greater headroom within a standard 3A cable path and at a voltage that aligns directly with the fixed USB-PD architecture.
That does not mean every OEM should move to 15V.
It does mean that automatically carrying 12V into the next generation of CPE deserves to be questioned.
With Regulation (EU) 2025/2052 applying from 14 December 2028, and new CPE platforms being designed today for deployment well beyond that date, this is precisely the point at which long-established power assumptions should be reconsidered.
12V became the CPE default for good reasons. USB-C PD may provide equally good reasons to choose differently.
For the next generation of CPE, 15V could be the smarter place to start.
At NetBit, we believe that question is worth asking now. To find out more about our products, email sales@netbit.com
