How to select a resettable fuse for the fan power supply of a data center switch?

Data center switch fans are typically powered by 12V/0.5A to 2A and require a series resettable fuse to prevent stall or short-circuit faults from escalating. Based on the operating current of 1.5A, the SMD1812-150-16V (holding current 1.5A, withstand voltage 16V, maximum fault current 100A, action time <5s@8A) is selected. This device, in an 1812 package, is suitable for high-density PCB layouts. When selecting, it is necessary to verify that the fan startup inrush current is typically 2 to 3 times the steady-state current, with a duration of <0.5s. The SMD1812-150-16V has a minimum operating current of 3A and will not trigger falsely during the startup cycle. Simultaneously, an SMBJ12CA TVS (VRWM=12V, clamping voltage 19.9V) is connected in parallel to absorb the fan back EMF spike. In actual testing, after stall protection, the PTC operates within 3.8 seconds, and automatically recovers after the fault is cleared.