Littelfuse

Littelfuse protection components in stock at YILUDA TECH. Nine Littelfuse lines are held as 100% original, new and unused material, covering TVS diodes, resettable PPTC fuses and surface-mount cartridge fuses.

What is listed

TVS diodes — SMCJ30A in SMC, SMF13A unidirectional in SMF.
PPTC resettable fuses — MINISMDC050F-2 and MINISMDC075F-2 in 1812.
Fuses — 0443002.DR and 0154003.DR at 2 and 3 A, 0154005.DR at 5 A, 0452003.MRL at 3 A.
Switch — JS202011JCQN slide switch.

TVS: three numbers, not one

SMCJ30A is a 30 volt standoff device in an SMC package with a 1500 watt peak pulse rating. The standoff voltage is the level the part tolerates continuously; the breakdown voltage is where it starts to conduct; the clamping voltage is what the protected circuit actually sees during a surge. Selecting on standoff voltage alone and ignoring clamp voltage is how a 3.3 V rail ends up protected by a device that lets 20 volts through to the IC. The A suffix marks a unidirectional part with a specified breakdown window, and replacing it with a bidirectional device changes both the clamp behaviour and the capacitance seen by the signal.

PPTC: hold and trip are different currents

A MINISMDC075F-2 holds 0.75 A and trips at a higher current, and both figures are specified at 25 degrees. In an enclosure running at 50 degrees the hold current falls meaningfully, so a fuse chosen at exactly the load current will nuisance-trip in the field. The right selection leaves margin on hold current and checks the trip time at the fault current the supply can actually deliver.

Fuse notes

Voltage rating and breaking capacity matter as much as the ampere rating on a DC rail.
The .DR and .MRL suffixes denote packaging, not electrical differences.
Worldwide shipping from Shenzhen by DHL, FedEx or UPS.