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Charging guide

Matching watts is necessary. Matching profiles is the real work.

USB Power Delivery is a negotiation between source and sink. A cable and every intermediate device add their own current and protocol boundaries.

Fixed profiles and programmable ranges

A fixed Power Data Object offers a specific voltage with a current ceiling. A Programmable Power Supply APDO offers a voltage range and current ceiling, allowing the device to request smaller voltage steps. PPS ranges stop at 21 V; newer SPR AVS and EPR AVS are distinct adjustable-voltage APDO types. “PPS supported” is incomplete unless the charger’s actual PPS range covers the device request.

Never combine rows. Voltage from one APDO and current from another do not form a valid operating point.

The current boundary

Power is voltage × current. A normal USB-C current path covers up to 3 A. More than 3 A requires a 5 A electronically marked C-to-C cable. Current certified cable branding uses 60 W and 240 W power markings; older compliant 100 W / 5 A products still exist.

Entered pointMinimum path implication
20 V × 3 A = 60 W3 A path; 60 W cable class
20 V × 5 A = 100 W5 A electronically marked cable
28 V × 5 A = 140 WEPR source, sink, and 240 W cable path
48 V × 5 A = 240 WMaximum USB PD power boundary

SPR and EPR are not product nicknames

Standard Power Range stays at 20 V or below. Extended Power Range adds higher voltage profiles up to 48 V and an overall 240 W ceiling. A dock advertising a large power supply does not automatically pass EPR to the host.

A safe decision sequence

  1. Find the device’s documented voltage/current profile or PPS range.
  2. Check one charger port under the exact occupied-port combination.
  3. Calculate required current and select the cable class.
  4. Verify PPS, EPR, or vendor-specific requirements separately.
  5. Treat the result as declared fit until negotiation is measured.

PD Requirement BuilderPPS Range CheckerCharge CheckSources & boundaries