A PoE switch with a power budget of 90 W can power 12 class 2 devices. Class 2 PoE devices typically require up to 7.5 W each. By dividing the total power budget (90 W) by the power requirement per device (7.5 W), we get 12 devices. This calculation aligns with the PoE standards defined in IEEE 802.3af/at, as outlined in Axis Communications' technical resources.