Glossary / USB-C
USB Power Delivery (USB-PD)
The protocol USB-C devices use to negotiate charging power.
USB Power Delivery (USB-PD) is the protocol USB-C devices use to negotiate how much power flows, expressed in volts and amps. The charger advertises a set of power profiles (PDOs) and the device requests one, forming a power 'contract'. Cablyst's PD Contract Inspector shows the agreed contract and every profile that was offered, so you can see exactly what capped your charging.
See it on your own cable — install Cablyst, check a cable, or browse the full glossary.
Related: E-marker Extended Power Range (EPR, 240 W) Thunderbolt 4 Thunderbolt 5 USB4 DisplayPort Alt Mode VDO (Vendor Defined Object) USB-IF (USB Implementers Forum) PDO (Power Delivery Object) SOP' (cable plug identity) UHBR (Ultra High Bit Rate) Active vs. passive cable