With all the electronic devices we handle every day of our lives, it is a pain to handle an equally large number of cables for charging them and transferring data. So far, a single standard connector to rule all the gadgets has proven to be elusive. A format war opens up, with one faction emerging victorious for a few years, until overtaken by another newer technology. For instance, Betamax overtook VHS, then DVD ousted Betamax, until Blu-ray overtook the DVD, and Blu-ray is now hardly visible with the onslaught of online streaming services.
As suggested by its acronym, the Universal Serial Bus, USB-C has proven to be different and possibly even truly universal. USB-C ports are now a part of almost all manner of devices, from simple Bluetooth speakers to external hard drives to high-end laptops and ubiquitous smartphones. Although all USB-C ports look alike, they do not offer the same capabilities.
The USB-C, being an industry-standard connector, is capable of transmitting both power and data on a single cable. It is broadly accepted by the big players in the industry, and PC manufacturers have readily taken to it.
USB-PD or USB Power Delivery is a specification for allowing the load to program the output voltage of a power supply. Combined with the USB-C connector, USB-PD is a revolutionary concept as devices can transmit both data and power as the adapter adjusts to the power requirements of the device to which it connects.
With USB-PD, it is possible to charge and power multiple devices, such as smartphones and tablets, with each device drawing only the power it requires.
However, USB-C and USB-PD are two different standards. For instance, the USB-C standard is basically a description of the physical connector. Using the USB-C connector does not imply that the adapter has USB-PD capability. Therefore, anyone can choose to use a USB-C connector in their design without conforming to USB-PD. However, with a USB-C connector, the user has the ability to transfer data and moderate power (less than 240 W) over the same cable. In addition, the USB-C connector is symmetrical and self-aligning, which makes it easy to insert and use.
Earlier USB power standards were limited, as they could not provide multiple levels of power for different devices. Using the USB-PD specifications, the device and the power supply can negotiate for optimum power delivery. How does that work?
First, each device starts with an initial power level of up to 10 W at 5 VDC. From this point, power negotiations start. Depending on the needs of the load, the device can transfer power up to 240 W.
In the USB-PD negotiation, there are voltage steps starting at 5 VDC, then at 9 VDC, 15 VDC, and 20 VDC. Beyond this, the device supports power output starting from 0.5 W up to 240 W, by varying the current output.
With USB-PD, it is possible to handle higher power levels at the output, as it allows a device to negotiate the power levels it requires. Therefore, USB power adapters can power more than one device at optimum levels, allowing them to achieve faster charge times.
