iPhone 16

Headroom Notes

Apple publishes two numbers for this port, and only the larger one is 4.5 W. Table 25-1 of the Accessory Design Guidelines gives iPhone 16 as 500 mA of USB Type-C Default current and 900 mA (4.5 W) over a USB Power Delivery contract. An accessory that does not negotiate PD gets 2.5 W — the same budget as a USB 2.0 port. iPhone 16 Pro advertises 900 mA even at Default; the non-Pro does not. Same connector, different power budget.

Production Warning

The practical question is not watts but whether the interface speaks USB PD. If it does not and needs more than 2.5 W, the phone will enumerate it and then drop it. The fix is a hub with its own power supply: the hub, not the phone, feeds the interface.