Product Overview
Littelfuse 251002 PICO II Axial Fuse, 2A at 125V, Very Fast-Acting
Condition
New. The photo shows a single olive-green epoxy body on a straight axial wire, printed in red, with bright untinted leads running full length on both sides and no bends, kinks, or oxidation. No packaging or labeling is visible in the photo and packaging is not confirmed here. The red body printing on the piece photographed reads "LF 1/4 A", a 1/4 amp marking, which does not match the 2A rating carried in our records for the 251002. We have flagged that difference rather than paper over it - ask us to confirm the marking on the piece in the bin before you order to a specific rating.
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Product Overview
The Littelfuse 251002 is a PICO II subminiature axial fuse rated 2 amps at 125 volts, built in the very fast-acting (VFA) characteristic. The whole device is a small molded body on two axial leads, so it installs like a quarter-watt resistor: through-hole into a board, into fuse clips, or spliced inline in a harness where a cartridge holder will not fit. Very fast-acting means it is chosen where a downstream semiconductor needs to be protected before the fault current has time to do damage, rather than where inrush must be ridden out. The 251 series part number is commonly written 251002, 0251002, and 251.002 across distributor catalogs and BOMs. Any rating beyond the 2A and 125V stated here is not confirmed - verify against the Littelfuse datasheet before use.
Key Features
- Manufacturer: Littelfuse
- Part number: 251002, PICO II series
- Current rating: 2A
- Voltage rating: 125V
- Characteristic: very fast-acting (VFA)
- Body style: subminiature axial, molded body on two straight wire leads
- Mounting: through-hole PCB, fuse clips, or inline splice
- Condition: New
- Interrupting rating, cold resistance, and melting I2t: not confirmed - verify against the datasheet before use
Applications
- Board repair technician replacing an open fuse on a legacy instrument PCB where the original was axial and there is no room for a 5x20 holder
- Instrument builder protecting a 125V or lower supply rail feeding sensitive semiconductors that need a fast opening fuse
- Avionics or test-gear maintainer matching an original PICO II callout on a drawing so the rebuild matches the print
- Prototype developer who wants one or two fuses on a breadboard supply rather than a full strip in a drawer
Frequently Asked Questions
What does "very fast-acting" change compared with a slow-blow fuse of the same rating?
A very fast-acting fuse opens sooner on an overcurrent, which is what you want when the thing downstream is a semiconductor rather than a motor or a transformer. If your circuit has a real inrush surge at power-up, a VFA part may nuisance-open where a time-delay part would hold. Match the characteristic the original design called for.
Will these leads go straight into a PCB?
Yes. The photo shows the leads straight and full length on both ends of the body, so they can be formed to your hole spacing and soldered through-hole, or trimmed and dropped into axial fuse clips. They arrive unformed, not pre-bent to any particular pitch.
Can I use it above 125V?
No. 125V is the rating stated for this part and it is the number to design to. Interrupting rating and the full time-current curve are not confirmed here - pull the Littelfuse datasheet for the 251 series and check them against your fault current before committing the part.
I need three fuses for one repair, not a strip of a hundred. Can I buy just that many?
Yes, and that is the point of stocking them here. There are 36 pieces on the shelf and you pick the number: one to get a dead board back on its feet, three so you have spares in the drawer, a dozen for a small production run. No forced pack of 50 or 100 and no minimum order. Shipping is $8 flat rate and free once your order passes $28, and orders leave our Idaho warehouse the same or next business day.
It looks like a quarter-watt resistor and behaves like a bodyguard, the one component on the board whose entire job is to fail before anything expensive does. Solder it in and, with any luck, you never think about it again.
