3.5 A hold in a 1206 footprint
The Littelfuse 1206L350SLTHYR is a polymeric PTC resettable fuse from the POLY-FUSE LoRho series, rated to hold 3.5 A continuously at 6 V and trip at 7 A. It clears a fault by heating up and jumping to a high-resistance state, protecting the downstream circuit without needing a fuse replacement after the overcurrent event clears. The 3.5 A hold current in a standard 1206 footprint means it fits into tight USB power ports, battery management paths, and low-voltage DC rails where a traditional fuse would take up more board space and require a holder.
What the ratings mean on the bench
After a trip event, the post-trip resistance climbs to 18 mOhms max, still low enough that the circuit can resume normal operation once the fault is removed and the PTC cools. The trip time is 5 seconds maximum at the rated fault current — this is a slow-blow response, so it will not nuisance-trip on inrush spikes from a capacitor bank or a motor start, but it will clear a sustained short before the downstream silicon sees junction damage. The 50 A maximum fault current rating means it can handle a dead short on a 6 V bus without rupturing. Derate the hold current at the high end of that range — a PTC's trip threshold drops as the ambient temperature rises, so at 85°C the effective hold current is lower than the 25°C rating.
Package and board-fit
The concave termination means the solder fillet wicks up the end of the part, giving a visible inspection point after reflow. Surface-mount only — no through-hole option. The low profile keeps it clear of any enclosure lid or secondary board stacked above.
Sourcing and compliance
Carries cURus and TUV approvals, meaning it is accepted for use in equipment sold into North America and the European Union without additional component-level safety testing.