1
Cartridge, Axial Lead, and Socket Fuses
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com for the most current information Revised: April 23, 2008
251/253 Series
PICO® II > Very Fast-Acting > 251/253 Series
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com/series/251.html or /253.html for current information.
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
Agency Agency File Number Ampere Range
®
E10480 62mA - 15A
®
LR 29862 62mA - 15A
PS
EJET 1896-31007-1001 1A - 5A
TUV J02037794 500mA - 10A
Features
Electrical Characteristics
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(62mA- 15A)
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temperature range
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% of Ampere
Rating Ampere Rating Opening Time
100% 1/16–15 4 hours, Minimum
200%
1/16–7 1 sec., Maximum
10 3 sec., Maximum
12-15 10 sec., Maximum
Applications
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
(mV)
Agency Approvals
®
®
PS
ETUV
1/16 .062 251.062 253.062 125
300 amperes
at rated
voltage VDC
50 amperes at
rated voltage
VAC
7.000 0.000113 1. 4 x x
1/8 .125 251.125 253.125 125 1.700 0.00174 0.285 x x
1/4 .250 251.250 253.250 125 0.665 0.0116 0.24 x x
3/8 .375 251.375 253.375 125 0.395 0.0296 0.215 x x
1/2 .500 251.500 253.500 125 0.280 0.0598 0.2165 x x x
3/4 .750 251.750 253.750 125 0.175 0.153 0.176 x x x
1 001. 251001. 253001. 125 0.128 0.256 0.194 x x x x
11/4 1.25 2511.25 125 0.100 0.390 0.2 x x x x
11/2 01.5 25101.5 25301.5 125 0.0823 0.587 0.21 x x x x
2 002. 251002. 253002. 125 0.0473 0.405 0.141 x x x x
21/2 02.5 25102.5 125 0.0360 0.721 0.132 x x x x
3 003. 251003. 253003. 125 0.0290 1.19 0.131 x x x x
31/2 03.5 25103.5 125 0.0240 1.58 0.1205 x x x x
4 004. 251004. 253004. 125 0.0204 2.45 0.114 x x x x
5 005. 251005. 253005. 125 0.0155 4.14 0.11 x x x x
7 007. 251007. 253007. 125 0.0105 10.4 0.102 x x x x
10 010. 251010. 253010. 125 0.00705 25.5 0.1 x x x x
12 012. 251012. 32 0.0055 45.2 0.0878 x x x
15 015. 251015. 253015. 32 0.00446 68.8 0.071 x x x
Electrical Characteristics
Note: Higher ampere ratings are available. Please contact Littelfuse Technical Support or your Littelfuse products representative for assistance.
RoHS
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PS
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Secondary protection for space constrained applications
TUV
®
2
Cartridge, Axial Lead, and Socket Fuses
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com for the most current information
Revised: April 23, 2008
251/253 Series
PICO® II > Very Fast-Acting > 251/253 Series
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com/series/251.html or /253.html for current information.
Average Time Current CurvesTemperature Rerating Curve
Soldering Parameters - Wave Soldering
100
10
1
0.1
0.01
0.001
1/16A
0.05 0.1 1 10 100 1000
1/8A
1/4A
3/8A
1/2A
3/4A
1A
1 1/2A
2A
2 1/2A
3A
3 1/2A
4A
5A
7A
10A
12A
15A
TIME IN SECONDS
CURRENT IN AMPERES
1 1/4A
Dwell Time
0
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
Time (Seconds)
Temperature (°C) - Measured on bottom side of board
Cooling Time
Preheat Time
Wave
Parameter Lead-Free Recommendation
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
Recommended Hand-Solder 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:
3
Cartridge, Axial Lead, and Socket Fuses
©2008 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com for the most current information Revised: April 23, 2008
251/253 Series
PICO® II > Very Fast-Acting > 251/253 Series
Specifications are subject to change without notice.
Please refer to http://www.littelfuse.com/series/251.html or /253.html for current information.
Materials
Encapsulated, Epoxy-Coated
Body: Wire Leads. 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 7 lb. axial pull test).
Moisture Sensitivity
Level J-STD 020 MSL Rating 2
Product Characteristics
Operating Temperature –55OC to 125OC
Shock
MIL-STD-202, Method 213, Test
Condition I (100 G’s peak for 6
milliseconds)
Vibration
MIL-STD-202, Method 201 (10–55
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Moisture Resistance MIL-STD-202, Method 106
Resistance to Soldering
Heat
Withstands 60 seconds above 200OC
and up to 260OC, maximum
Flammability Rating UL 94V0
F
L
F
L
1 A
F
L
1 A
1 A
27.78
(1.094")
27.78
(1.094")
7.11 (.280")
62.7 (2.468")
52.4 (2.062")*
253 series markings
251 series markings
**0.64 (.025") 2.80 (.11")
6.35 (.25")
tape
5.0 (.197")
6.35 (.25")
tape
Dimensions
Packaging
Part Numbering System
Packaging Option Packaging Specification Quantity &
Packaging Code
*T1: 52.4mm (2.062") Tape and Reel EIA 296 1MFBTFSFGFSUPBWBJMBCMFRVBOUJUJFT
above in "Part Numbering System”
0251 xxxx N R T1 L
RoHS
Lead Length
Type of Packaging
Quantity
Current Rating
Series
T1: 52.4mm (2.062”)*
R = Reel
A = Ammo Pack
X = Loose Pack
N = 5000
P = 2000
M = 1000
H = 100
V = 5
Refer to Amp Code column of
Electrical Characteristics Table
251 = Standard type
253 = Military type
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** .025” diameter for 1/16–10A, .032” diameter for 12–15A.