© 2018 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 05/31/18
Axial Lead & Cartridge Fuses
PICO® ll > Very Fast-Acting Fuse > 251/253 Series
251/253 Series, PICO® II Very Fast-Acting Fuse
Description
The PICO® II Very Fast-Acting Fuse is designed to meet an
extensive array of performance characteristics in a
space-saving subminiature package.
Agency Approvals
Features
Electrical Characteristics for Series
% of Ampere
Rating Ampere Rating Opening Time
100% 0.062A - 15A 4 Hours, Min.
200%
0.062A - 7A 1 Second, Max.
10A 3 Seconds, Max.
12 - 15A 10 Seconds, Max.
275%
0.500A, 1A, 2A,
2.5A, 3A, 4A, 5A,
7A, 10A
300 msecs., Max.
400% 0.5A, 1A, 2A, 2.5A,
3A, 4A, 5A, 7A, 10A 30 msecs., Max.
1000%
0.500A, 1A, 2A,
2.5A, 3A, 4A, 5A,
7A, 10A
4 msecs., Max.
Applications
PS
E
• Flat–panel display TV
• LCD monitor
• LCD backlight inverter
• Office machines
• Power supply
• Audio/Video system
• Lighting system
• Medical equipment
Secondary protection for space constrained applications
QPL
• Very fast-acting
• Small size
• Wide current rating range
(0.062A- 15A)
• Halogen-free available
• Wide operating
temperature range
• Low temperature re-rating
Application testing is strongly recommended.
Agency
Agency File Number
Ampere Range
253 Series 251 Series
E10480 0.062A - 15A
29862 0.062A - 15A
PS
EPSE_NBK200416-JP1021 1A - 5A
J50158379 0.500A - 10A
FM10 N/A 0.062A - 15A
2009010207366577 0.500A, 1A, 2A,
2.5A, 3A, 4A, 5A
Note: See Electrical Specifications by Item table for specific approved ratings.
Additional Information
Datasheet Samples
Resources
Datasheet Samples
Resources
251 Series
253 Series
251 Series
253 Series
251 Series
253 Series
© 2018 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 05/31/18
Axial Lead & Cartridge Fuses
PICO® ll > Very Fast-Acting Fuse > 251/253 Series
Electrical Specifications by Item
Note: Higher ampere ratings are available. Please contact Littelfuse Technical Support or your Littelfuse products representative for assistance.
Ampere
Rating
(A)
Amp
Code
Ordering
Number
(Std.)
Ordering
Number
(Mil.)
Max
Voltage
Rating
(V)
Interrupting
Rating
Nominal
Cold
Resistance
(Ohms)
Nominal
Melting
I2t (A2 sec)
Nom
Voltage
Drop
(V)
Agency Approvals
PS
E
QP
L
253 Series
Only
.062 .062 251.062 253.062 125
300 A @
125VDC
50A@125VAC
7.000 0.000113 1. 4 x x x
.125 .125 251.125 253.125 125 1.700 0.00174 0.285 x x x
.200 .200 251.200 253.200 125 0.895 0.0048 0.345 x x
.250 .250 251.250 253.250 125 0.665 0.0116 0.24 x x x
.375 .375 251.375 253.375 125 0.395 0.0296 0.215 x x x
.500 .500 251.500 253.500 125 0.302 0.0598 0.2165 x x x x x
.630 .630 251.630 125 0.205 0.08 0.188 x x
.750 .750 251.750 253.750 125 0.175 0.153 0.176 x x x x
1. 0 0 0 01. 251001. 253001. 125 0.128 0.256 0.194 x x x x x x
1.25 1.25 2511.25 125 0.100 0.390 0.2 x x x
1.50 01. 5 25101.5 25301.5 125 0.0823 0.587 0.21 x x x x x
2.00 002. 251002. 253002. 125 0.0473 0.405 0.141 x x x x x x
2.50 02.5 25102.5 125 0.0360 0.721 0.132 x x x x x
3.00 003. 251003. 253003. 125 0.0295 1. 19 0.131 x x x x x x
3.50 03.5 25103.5 125 0.0240 1.58 0.1205 x x x x
4.00 004. 251004. 253004. 125 0.0204 2.45 0.114 x x x x x x
5.00 005. 251005. 253005. 125 0.0158 4.14 0.11 x x x x x x
7. 0 0 0 0 7. 251007. 253007. 125 0.0107 10.4 0.102 x x x x
10.0 010. 251010. 253010. 125 0.0072 25.5 0.1 x x x x
12.0 012. 251012. 32 0.0059 45.2 0.0878 x x
15.0 015. 251015. 253015. 32 0.00446 68.8 0.071 x x x
300A@32VDC
& 50A@32VAC
© 2018 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 05/31/18
Axial Lead & Cartridge Fuses
PICO® ll > Very Fast-Acting Fuse > 251/253 Series
Average Time Current Curves
Soldering Parameters
100
10
1
0.1
0.01
0.001
.062A
0.05 0.1 110100 1000
.125A
.250A
.375A
.500A
.750A
.630A
1A
1.5A
2A
2.5A
3A
3.5A
4A
5A
7A
10A
12A
15A
TIME IN SECONDS
CURRENT IN AMPERES
1.25A
Recommended Hand Soldering Parameters:
Solder Iron Temperature: 350°C +/- 5°C
Heating Time: 5 seconds max.
Note: These devices are not recommended for IR or
Convection Reflow process
Recommended Process Parameters:
Note:
1. Re-rating depicted in this curve is in addition to the standard derating of 25% for
continuous operation.
Temperature Re-rating Curve
Wave Parameter Lead-Free Recommendation
for 251 Series only
Preheat:
(Depends on Flux Activation Temperature) (Typical Industry Recommendation)
Temperature Minimum: 100°C
Temperature Maximum: 150°C
Preheat Time: 60-180 seconds
Solder Pot Temperature: 260°C Maximum
Solder Dwell Time: 2-5 seconds
© 2018 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 05/31/18
Axial Lead & Cartridge Fuses
PICO® ll > Very Fast-Acting Fuse > 251/253 Series
Materials
Encapsulated, Epoxy-coated Body
251 Series: Pure tin-coated copper wire leads
253 Series: Solder-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
Withstands 60 seconds above 200OC
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 = 10 0
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 0.062-10 amp,
0.81 (.032") for 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)
L1 A
L1 A
73.0 (2.874")**
Wire Diameter:
0.64 (.025") for 0.062-10 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)
Wire Diameter:
0.64 (.025") for 0.62-10.0 amp,
0.81 (.032") for 12-15 amp
L1 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 (Halogen-free Version) Markings
(T1 lead length)
F
F
F
Disclaimer Notice - Information furnished is believed to be accurate and reliable. However, users should independently evaluate the suitability of and test each
product selected for their own applications. Littelfuse products are not designed for, and may not be used in, all applications. Read complete Disclaimer Notice at:
www.littelfuse.com/disclaimer-electronics.
