© 2016 Littelfuse, Inc.

Specifications are subject to change without notice.

Revised: 10/10/16

Axial Lead & Cartridge Fuses

Materials

Encapsulated, Epoxy-Coated

Body: Pure Tin-coated Copper wire leads

Solderability

MIL-STD-202, Method 208

Lead Pull Force

MIL-STD-202, Method 211, Test Condition

A (will withstand a 7lbs. axial pull test)

Fuses To MIL SPEC

For fuses to MIL-PRF-23419, FM10

change the series number from

251 to 253

Operating

Temperature

–55ºC to +125ºC (Consider re-rating)

Product Characteristics

Vibration

MIL-STD-202, Method 201 (10–55

Hz); Method 204, Test Condition C

(55–2000 Hz at 10 G’s Peak)

Shock

MIL-STD-202, Method 213, Test

Condition I (100 G’s peak for 6

msecs.)

Insulation Resistance

(After Opening):

MIL-STD-202, Method 302,

Test Condition A (10,000 ohms

minimum at 100 volts)

Moisture Resistance

MIL-STD-202, Method 106

Resistance to Soldering

Heat

and up to 260ºC, maximum

Flammability Rating

UL 94V–0

Dimensions

Packaging

Part Numbering System

Packaging Option

Packaging Specification

Quantity &

Packaging Code

*T1: 52.4mm (2.062") Tape and Reel

EIA 296

Please refer to available quantities

above in "Part Numbering System”

**T3: 73mm (2.874') Tape and Reel

EIA 296

0251 xxxx N R T1

Lead Length

Type of Packaging

Quantity

Current Rating

Series

The default lead length for Ammo pack and

Loose pack is now T1 for 251 series, and

remains T3 for 253 series, therefore:

T1 = 52.4mm (2.062”), 251 series only*

Blank = 52.4mm (2.062”) for 251 series*

or 73mm (2.874”) for 253 series**

R = Reel

A = Ammo Pack

X = Loose Pack

N = 5000

P = 2000

M = 1000

H = 100

Refer to Amp Code column of

Electrical Specifications Table

251 = Standard type

253

= Military type

Option Codes

L

L = RoHS + HF

(Only applies to 251 Series)

The default lead length for both ammo pack and loose pack is T1 for 251 and is T3 for 253.

Notes:

* T1 dimension is defined as the length of the component between the two tapes. The full component length is 62.7mm (2.468"). T1 length is for 251 series only.

** T3 dimension is defined as the length of the component between the two tapes. The full component length is 83.3.7mm (3.28”). T3 length is for 253 series only.

Wire Diameter:

0.64 (.025") for 0.62-10.0 amp,

0.81 (.032") for 15 amp

Wire Diameter:

0.64 (.025") for 0.62-10.0 amp,

0.81 (.032") for 12-15 amp

2.61 (.103")

MAX

6.35 (.25")

tape

5.0 (.197")

6.35 (.25")

tape

38.1

(1.5")

38.1

(1.5")

7.11 (.280")

83.31 (3.28")

253 Series Markings

(T3 lead length)

73.0 (2.874")**

F

L

1 A

27.78

(1.094")

27.78

(1.094")

7.11 (.280")

62.7 (2.468")

52.4 (2.062")*

2.80

(.11")

MAX

6.35 (.25")

tape

5.0 (.197")

6.35 (.25")

tape

251 Series (Halogen-free Version) Markings

(T1 lead length)

Wire Diameter:

0.64 (.025") for 0.62-10.0 amp,

0.81 (.032") for 12-15 amp

F

L

1 A

F

L

1 A

27.78

(1.094")

27.78

(1.094")

7.11 (.280")

62.7 (2.468")

52.4 (2.062")*

2.80

(.11")

MAX

6.35 (.25")

tape

5.0 (.197")

6.35 (.25")

tape

251 Series Markings

(T1 lead length)

F

F

F