The risk for fire or shock is much greater. And potentially more dangerous as the Amps increase to as much as 20 A. You can imagine this makes Power Delivery more challenging to implement.

When the PC goes into a lower power mode or sleep mode, the hub or the PC can negotiate and reduce the power and then the power can be more evenly be distributed to all devices for charging. The charger can reduce power to charge the tablet and phone while the PC needs the power. The PC can request more power from the charger. The PC might need more power to operate during usage while the tablet and phone are trying to quick charge. The reason this is useful is if you had a PC and a tablet and a phone all plugged into a single hub. For example, a sink can request more power if it needs more, and the source can ask the sink what it’s minimum power requirements are. In some cases the Sink (like the PC or phone) can tell the source how much to power to provide. Then they can operate at the highest levels to maximize power throughput. The exchange is done twice to make sure it’s safe. Power Adapters (Source) report to devices (Sink) their explicit PD Power (PDP) capabilities. To charge at the higher rates safely, the USB IF and IEC developed a system to allow for power supplies and devices to exchange information on their capabilities.

This allows the charger to support the nominal voltage of 5 V and a maximum of 20 A to supply a maximum of 100W. It can be implemented with either a fixed voltage or using a programmable power supply. USB Power Delivery really defines the standard above 15W. (As a reminder, the Battery Charging specification which supported 7.5W is not applicable for Type-C) This effectively replaces the Battery Charging standard.) This really doesn’t require USB Power Delivery as it’s defined already in the USB Type-C specification. For this example, we will say we have two kinds a 15W and a 45 W charger.įor 15W, the charger must support 5 V and a maximum of either 1.5 or 3.0 A for a total of 7.5 or 15 W maximum charging. With USB Power Delivery, the USB IF has defined two new logos for Charger, either a Charger or a Fast Charger designation along with the supported Wattage. USB 2.0 with 5 V and at 500mA for total of 2.5W USB 3.2 with 5 V and either 900mA or 1,500mA for a total of either 4.5W or 7.5W The Default USB Power that must be supported is That means lots of cables: Here’s the ones that can think of We’ve just returned from USB Developers Days in Vancouver, B.C.Īnother day on USB Authentication and USB Power Delivery.

Usb 2 vs usb 3 charging