USB Power Delivery (for Set top Boxes) - A dream so close and yet, so far away

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Problem 2: The STB business case

On what regards to STBs, what matters is the total cost of ownership, of which, the actual bill of materials is the biggest component, but not by far the only one. Equally important are costs such as customer care, logistics, reverse logistics and processes, and the USB-C power delivery hits a few of them, that is, until EU forces a change, as is so often the case.

The use case for USB-C is to take advantage of an already existing power supply on the TV, sparing the cost of an external dedicated power supply, an HDMI cable, PSU DC cable and Ethernet cable.

Starting by the latter, Ethernet over USB-C is still not available, even from a standard point of view. Although it would solve some problems on its own: the STB is always far closer to the TV rather than the home gateway. However HDMI does support Ethernet over HDMI, although limited to 100Mbps, and the USB-C alternate mode does support all of the features from HDMI 1.4 including CEC and HEAC, also known as Ethernet over HDMI.

Then, HDMI. As described above, is supported as an USB-C alternate mode, but limited to HDMI 1.4, which today is useless. The fact of the matter is that current HDMI implementations are based on HDMI 2.0 which the minimum version required for 4K support. This makes the case for the high end products simply not feasible.

In terms of cables, things are not that clear. A certified HDMI High-speed cable can be bought at less than 2€ on volume purchases, however, a brand new HDMI 2.1 Ultra High Speed HDMI cable can hardly be purchased below 8€, even on wholesale, mainly due to the lack of volume production of such cables. On the other hand, volume production of USB-C cables is well established, where a high quality, 5 Amp charging cable can be found well below 2€.



Finally, the most basic item: the power supply unit. And it’s here where the biggest problem comes from. Adding the other features based on USB-C technologies doesn’t significantly increase the hardware bill of materials, except for the PSU.

A cheap 12V 2A PSU goes for little more than 3€, without volume discount. But USB-C based PSUs are in a totally different ballpark, from around 9€ for the equivalent 30W unit, to 10€ for a high powered 60W USB-C PD supply. The point being, until two thirds of users use their own power supply, the additional flexibility offered by USB PD won’t allow for cost cutting, not including the logistics associated with not including the PSU on all devices, which is often not irrelevant.

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