USB Power Delivery PPS – The charging standard can do this!

Many of you are probably already familiar with USB Power Delivery. The standard, abbreviated to PD, is responsible for high charging performance and for the quick charging function via USB-C on the iPhone, for example, but also on the iPad and MacBook. In the third generation, Power Delivery 3, further specifications were added, including the Programmable Power Supply (PPS). Although this has been around for a few years, it is not yet widely used. But that is changing bit by bit. Therefore, this article clarifies: What is USB Power Delivery PPS and what can the charging standard do?

USB Power Delivery PPS can do that

Programmable Power Supply is an optional protocol that can be used since Power Delivery 3.0. This means that all chargers and power banks with PPS have PD 3. But not all chargers and external batteries with PD 3 automatically have PPS. But that's just a hint to get you started on the - once again - slightly complicated subject. 

But what can the PPS protocol do? It allows finer adjustment of the voltage from 3,3 V to 21 V in 20 mV steps. This allows real-time adjustment during charging and maintains a constant charging power, even with increasing or decreasing current. 

In addition to the constant performance, increasing or decreasing charging performance can also be achieved in smaller steps, depending on the charge level of the battery and other factors - for example, the battery temperature can be included in order not to overheat the component.

It is also important to know that with Power Delivery 3.1 in 2021, the Extended Power Range (EPR) was added to the PD standard. This not only allows up to 48 volts at up to 5 Ampere, i.e. theoretically up to 240 watts. The voltage can also be adjusted between 15 V and 48 V in 100 mV steps thanks to PPS and the extension called Adjustable Voltage Supply (AVS). 

All this also benefits the individual hardware elements, as fine adjustments can be made at any time for the optimal charging performance depending on the situation. The efficient charging achieved in this way also reduces the heat generated in the charger - so, to put it simply, more electricity goes into the end device and not as much heat radiated into the air.

Standard values ​​for charging power from 0,5 to 240 watts

As already described above, PPS chargers and the devices to be charged can negotiate individual charging capacities. These are then made up of higher voltage and lower current or vice versa, depending on requirements. For the quick charge function, thanks to which the iPhone is currently e.g. B. only 30 minutes for 50% battery charge, of course, a lot of current has to flow quickly. From 80%, however, the whole thing is throttled so that the battery does not end up at 100% and overcharge so quickly. This is currently happening without PPS, but will be even more efficient in the future.

So far, so well known. But it is also interesting which standard values ​​are actually used for Power Delivery, even if no PPS is used. In the following table you will find an overview that shows the Standard Power Range (SPR) up to 100 W in the upper area and the Extended Power Range (EPR) up to 240 W in the lower area. It is shown from top to bottom how 0,5 to 240 W can be achieved - from 5 V to 48 V with the respective variable current levels. This table can be used both with and without PPS. However, the latter is not a must, as you will see in the following explanations.

Note: These are only default values ​​that are used without optional protocols. Different solutions are possible.

More variable values ​​possible with PPS chargers

The table above probably explains why some chargers have such strict values ​​for the current output. Again and again one finds information that e.g. For example, 5V is up to 3A (15W), 9V is up to 3A for faster charging (27W), or 15V is up to 3A for a maximum of 45W be used. 

On PPS-enabled devices, however, you'll find more specific volt ranges and more variable amp ratings, around 4,05 A for 3,3 to 11 V (13,37 - 44,55 W). You may also encounter 2,8 A for 3,3 to 16 V (44,8 - 52,8 W). I've also seen 2,1 A for a range of 3,3 to 21 V (6,93 - 44,1 W). As described above, charging should be better individualized here and adapted to the respective circumstances in real time.

PPS can complicate the charger selection

As an interim conclusion, we can say that PPS should make charging via a USB-C port and the "Power Delivery" standard more efficient and better overall. However, you have to take a closer look at the respective volt and ampere ranges for chargers or power banks with USB Power Delivery PPS. Then some ampere limitation for a certain volt range can mean a maximum power below the power of the end device required for fast charging. Despite more variable values, the charger cannot do as much as the smartphone or tablet needs.

Briefly explained using an example, this means: A terminal device requires, for example, 9,5 V at 4 A (38 W) for the quick charging function and quick charging of its battery. The voltage of 9,5 V should be fixed or only slightly adjusted. If a PPS charger now offers a maximum current of 3,3 A for the voltage range from 21 to 3 V, then a maximum of 9,5 W is supplied at 28,5 V, i.e. 9,5 W less than for the maximum loading speed required. 

If the charging process is not as flexible as the charger or if the charger is not adaptable enough for the end device, then the technology will not work together satisfactorily.

SPR and EPR cables - Can it be a little more complicated?

Now that we know roughly what makes PPS chargers so special and what terminal devices think of them in case of doubt, we still have to take a look at the connection technology. Because of course you can't just use any x-any for the different standards (PD 2.0, PD 3.0 and PD 3.1) as well as for the individual protocols (PPS, AVS, etc.). USB-C cable to use. That would be too easy. Retrospectively, these rather simple cables from the junk box were referred to as "SPR cables"; models that are only designated as “EPR cables” can handle 5 amps and thus the highest charging capacities.

Summary of USB Power Delivery PPS

When in March 2021 I Comparison of PD 2.0 and PD 3.0 I wanted to sum it up with the words "When you find out about USB, you get a lot of different terms and numbers." tried. This was a bit tied to the hope that subsequent updates to the PD standard would be easier. But wrong thought. Ultimately, we can summarize this: PPS provides more individual charging performance, which should allow real-time adjustment to certain factors and device specifications. This should also make the chargers more efficient. However, there may be compatibility problems if you are not careful.

Sources: 1, 2

Johannes Domke

[On vacation] After graduating from high school, Johannes completed training as a business assistant specializing in foreign languages. But then he decided to research and write, which led to his independence. He has been working for Sir Apfelot, among others, for several years now. His articles include product introductions, news, instructions, video games, consoles and much more. He follows Apple keynotes live via stream.