In the age of USB-C, the universal charger is king. Laptops, phones, tablets, so many devices are adopting the USB-C port for its versatile functionality and ability to carry high levels of power.
Developed by the USB Implementation Forum (USB-IF: the bigwigs behind all USB device standards), USB Power Delivery (USB-PD) is capable of delivering both high power to laptops and low power to your mobile phone.
But what is USB-PD? How does it work? What does it do?
- Device that supports USB-PD
- Charger that supports USB-PD
How does USB-PD work?
When you connect a USB-PD charger to a device that supports the USB-PD charging standard, the charger initially supplies the device with the standard 5 Volts, traditionally found in USB devices.
It speaks with the device
After being plugged in, the charger communicates with the USB-PD device, asking for the device’s maximum supported charging voltage. The USB-PD device responds by communicating this information to the USB-PD charger.
It gives the device the power it needs
Having received the charging specifications from the device, the charger starts to output the required power to the device. USB-PD can output the standard 5 Volts you expect from your average USB supply, all the way up to 20 Volts (common laptop voltage), with a maximum current of 5 Amps (100 Watts).
The table below shows the current power profiles that USB-PD chargers support.
|Voltage||Maximum Current (Amps)||Maximum Power (Watts)|
E-Marker IC Chip
For a USB-C cable to carry at least 5A of power, a chip known as the E-Marker chip must be installed inside one of the USB connectors. The charging device communicates with the chip, to ensure the cable is USB-PD compliant.
Key advantages of USB-PD
Although Qualcomm’s Quick Charge (QC) standard is a fantastic charging solution, USB-PD has several advantages over QC.
Thanks to USB-PD’s ability to supply up to a whopping 100W and ability to communicate with compatible devices, even USB-PD laptop chargers can fulfil the power requirements of less-demanding devices (e.g. phones).
Some manufacturers are modifying their charging circuitry to prevent the use of 3rd party chargers. Although this could be interpreted as forcing consumers to pay a premium for manufacturer approved products, this also enables the manufacturer to provide a level of quality control and prevent consumers from voiding their warranties.
It’s both practical and environmentally friendly
Adopting USB-PD simplifies the process of purchasing a laptop charger and helps to reduce electrical waste. It’s also nice to carry fewer cables in your backpack!
It multitasks & goes both ways
Data and power transfer can occur simultaneously over the same cable. USB-PD even allows power to flow in both directions, making it possible to share power between devices from the same port!