Today Qualcomm announces a new commercial fast charging solution in the form of Quick Charge 5, taking advantage of the latest technological developments in charging circuits and taking advantage of USB power delivery. Programmable Power Supply (PD-PPS) standard to achieve load powers of up to 100W.
We’ve all been familiar with Quick Charge and its various implementations over the years, innovating beyond the classic 5W USB power delivery limits more than 7 years ago. In recent years, we’ve seen maximum charging speeds continually improve, from 10W in Quick Charge 1.0, to 18W in 3.0, up to 27W in recent 4.0-certified chargers using USB-PD.
Today for Quick Charge 5, Qualcomm is again changing the charger and PMIC architecture to be able to quadruple charging speeds, allowing up to 100W of charging power.
Fundamentally, a big change over the years for Quick Charge as a branded Qualcomm fast charge standard is that as of QC4.0 the company has changed from its own proprietary charge negotiation protocol (essentially what it originally was Quick Charge), to Standard USB-PD (Power Supply), with the product branding as a general certification platform as well as a charging solution by the phone’s internal charging architecture.
Today’s new Quick Charge 5 in that regard is an evolution of what the USB-PD PPS standard offers (to note: QC4 was already compatible with PD-PPS, although it was not actively used as a voltage adjustment protocol) , taking full advantage of the specification voltage ranges to supply power up to 100W.
In a USB PD-PPS solution, the charging architecture changes more fundamentally as we see some voltage regulations move from the inside of the phone by internal PMICs to the inside of the actual charger, which is now more complex and flexibility in terms of the voltages it can provide This is a part of QC5 and what PD-PPS enables to achieve higher charging speeds, by moving part of the conversion loss from inside the phone into the charger.
The second part of Quick Charge 5 is not so much the charging adapters or the communication protocol itself, but the charging architecture inside the phone. Qualcomm’s new addition with the new SMB1396 flip cap converters and new SMB1398 PMIC battery is the fact that they are designed to support 2S battery systems, meaning dual cell batteries that are connected in series. The advantage of using this approach is that it raises the system charging voltage to twice that of a single battery cell, moving from the 4.4V to 8.8V example.
This in turn allows you to double the input voltage on the phone, avoiding or alleviating a crucial limitation for power delivery on a USB device – the cable itself, which only supports up to 3-5A on most cables.
The QC5 platform allows an input voltage of up to 20V. Essentially with a standard lithium cell charging voltage at ~ 4.4V, doubling this with the help of dual series cell architecture at ~ 8.8V, and allowing only a flip-cap 2: 1 conversion stage inside the phone , the charger could generate ~ 17.6V at around 5.6A to be able to reach a load of 100W. Overall, that’s more than most cables will support, so Qualcomm’s max figure here is likely to be just in an ideal scenario. Any standard cable handling up to 3A would easily support a load of up to 53W, for example.
Qualcomm claims that QC5 can be up to 10 ° C colder, 70% more efficient, and 4 times faster than QC4. All of these figures are primarily achieved by adopting more efficient conversion techniques and shifting some of the voltage conversion work to the power adapter. The limitation within a phone is heat dissipation, with Qualcomm here using a charging temperature of 40 ° C as its own self-imposed limitation on how hot a device can get hot. Most of this heat is generated by the PMICs inside the phone, as the battery itself does not heat up during charging.
The charging circuits of the new PMICs enable a traditional 3-level buck converter together with a 2: 1 / DIV / 2 switched limit converter to provide a maximum quoted conversion efficiency of over 98%. (In order to maintain a temperature of 40 ° C, a phone can only dissipate 3-4W at most in my experience.)
QC5 does not dictate that vendors need to use 2S battery designs, and most vendors are unlikely to use them due to additional battery volume overload from using two cells (less total capacity), as well as the fact that Discharge inefficiency has been added due to having to convert from a higher operating voltage (~ 8.4V vs 4.2V) during use, also indirectly decreasing the usable power capacity of the batteries.
Smartphones that still use single battery cells will see advantages in charging and thermal speeds, although Qualcomm here states that they will generally be limited to a maximum power of around 45W.
I asked the company if battery technologies and chemistries have advanced to the point where the use of such high charging speeds will not degrade the holding capacity of the cells, and the answer was “yes”, although it lacked details or details. In conversations with other independent industry sources in general, it is agreed, although over the years there have been improvements in lithium cell technology, these recent generations of very high power charging primarily carry a cost of further degradation of the battery, which is why I’m still very skeptical of these recent charging standards, and why I see that major providers like Apple or Samsung aren’t participating in this race.
In terms of device and accessory compatibility, although the above matrix seems relatively complex, it is quite simple, as a device will simply charge as fast as a given adapter allows, and the fast charge capability is simply broken down into DC protocols. (DC)<=3) and USB-PD protocols (QC=>4) The newer QC 4+ to 5 charger will continue to support proprietary legacy protocols and allow fast charging of such devices.
What’s great about QC5 and the fact that it uses PD-PPS as its underlying protocol is that you don’t really need a QC5 charger to be able to charge your device at QC5 speeds. A generic PD-PPS charger with the correct voltage and current range will suffice and be fully compatible. For example, OPPO’s recent iteration of its fast charging systems takes advantage of USB PD-PPS as a protocol, with adapters that support up to 20V 6.3A, which essentially makes it compliant with standards and in theory should be fully compliant. with any QC5 device, or vice versa. Vice versa, any newer OPPO device must be compatible with QC5 adapters, leaving the only proprietary and problematic technology to be any special cables that support currents greater than> 3A.
Overall, Quick Charge 5 doesn’t bring anything inherently new that hasn’t been introduced by some of the most aggressive Chinese vendors on the market, like OPPO, but it does it in a welcome, standards-compliant way through PD-PPS, and also offering the device-side commercial PMIC architecture to enable these insanely high new upload speeds.
