Axial Lead & Cartridge Fuses
PICO
®
ll > Very Fast-Acting > 251/253 Series
251/253 Series, PICO
®
II, Very Fast-Acting Fuse
Description
PS
E
QPL
The PICO
®
II Very Fast-Acting Fuse is designed to meet an
extensive array of performance characteristics in a
space-saving subminiature package.
Features
• Very fast-acting
• Halogen-free available
• Small size
• Wide operating
temperature range
• Wide current rating range
(62mA- 15A)
• Low temperature rerating
Agency Approvals
Agency
Agency File Number
Ampere Range
Applications
Secondary protection for space constrained applications
• Flat–panel display TV
• LCD monitor
• LCD backlight inverter
• Office machines
• Power supply
• Audio/Video system
• Lighting system
• Medical equipment
E10480
62mA - 15A
62mA - 15A
1A - 5A
500mA - 10A
62mA - 15A
500mA, 1A, 2A, 2.5A,
3A, 4A, 5A
LR 29862
PS
E
JET1896-31007-1004
J50158379
Electrical Characteristics for Series
% of Ampere
Rating
100%
200%
Ampere Rating
62mA - 15A
62mA - 7A
10A
12 - 15A
500mA, 1A, 2A,
2.5A, 3A, 4A, 5A,
7A, 10A
500mA, 1A, 2A,
2.5A, 3A, 4A, 5A,
7A, 10A
500mA, 1A, 2A,
2.5A, 3A, 4A, 5A,
7A, 10A
Opening Time
4 Hours, Min.
1 Second, Max.
3 Seconds, Max.
10 Seconds, Max.
300 msecs., Max.
30 msecs., Max.
4 msecs., Max.
QPL
FM10
2009010207366577 –
500mA to 5A
Additional Information
275%
400%
Datasheet
251 Series
Resources
251 Series
Samples
251 Series
1000%
Datasheet
253 Series
Resources
253 Series
Samples
253 Series
© 2014 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 03/10/14
Axial Lead & Cartridge Fuses
PICO
®
ll > Very Fast-Acting > 251/253 Series
Temperature Rerating Curve
Average Time Current Curves
.250A
.375A
.500A
.630A
.750A
1A
1.25A
1.5A
2A
2.5A
3A
3.5A
4A
5A
7A
10A
12A
15A
1
10
CURRENT IN AMPERES
100
.062A
.125A
100
10
TIME IN SECONDS
Note:
1. Rerating depicted in this curve is in addition to the standard rerating of 25% for
continuous operation.
1
0.1
0.01
Soldering Parameters
Recommended Process Parameters:
Wave Parameter
Preheat:
(Depends on Flux Activation Temperature)
(Typical Industry Recommendation)
0.001
0.05 0.1
1000
Lead-Free Recommendation
for 251 Series only
Temperature Minimum:
Temperature Maximum:
Preheat Time:
Solder Pot Temperature:
Solder Dwell Time:
100
°
C
150
°
C
60-180 seconds
260
°
C Maximum
2-5 seconds
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
© 2014 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 03/10/14
Axial Lead & Cartridge Fuses
PICO
®
ll > Very Fast-Acting > 251/253 Series
Product Characteristics
Materials
Solderability
Lead Pull Force
Fuses To MIL SPEC
Operating
Temperature
Encapsulated, Epoxy-Coated
Body: Pure Tin-coated Copper wire leads
MIL-STD-202, Method 208
MIL-STD-202, Method 211, Test Condition
A (will withstand a 7lbs. axial pull test)
251/253 Series is available in FM10 on
QPL for MIL-PRF-23419. To order, change
251 to 253
–55ºC to +125ºC
Shock
Insulation Resistance
(After Opening):
Moisture Resistance
Resistance to Soldering
Heat
Flammability Rating
Vibration
MIL
-STD-202, Method 201 (10–55
Hz); Method 204, Test Condition C
(55–2000 Hz at 10 G’s Peak)
MIL
-STD-202, Method 213, Test
Condition I (100 G’s peak for 6
msecs.)
MIL
-STD-202, Method 302,
Test Condition A (10,000 ohms
minimum at 100 volts)
MIL
-STD-202, Method 106
Withstands 60 seconds above 200
O
C
and up to 260ºC, maximum
UL 94V–0
Dimensions
251 Series Markings
(T1 lead length)
62.7 (2.468")
52.4 (2.062")*
7.11 (.280")
Part Numbering System
0251 xxxx N R T1 L
27.78
(1.094")
27.78
(1.094")
Series
1A
6.35 (.25")
tape
5.0 (.197")
F
L
251
= Standard type
253
= Military type
2.80
(.11")
MAX
6.35 (.25")
tape
Current Rating
Refer to Amp Code column of
Electrical Specifications Table
1A
F
L
Wire Diameter:
0.64 (.025") for 0.62-10.0 amp,
0.81 (.032") for 12-15 amp
Quantity
N
= 5000
P
= 2000
M
= 1000
H
= 100
251 Series (Halogen-free Version) Markings
(T1 lead length)
62.7 (2.468")
52.4 (2.062")*
7.11 (.280")
27.78
(1.094")
27.78
(1.094")
Type of Packaging
R
= Reel
A
= Ammo Pack
X
= Loose Pack
F
L
6.35 (.25")
tape
5.0 (.197")
1A
2.80
(.11")
MAX
6.35 (.25")
tape
1A
F
L
Lead Length
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**
Wire Diameter:
0.64 (.025") for 0.62-10.0 amp,
0.81 (.032") for 12-15 amp
253 Series Markings
(T3 lead length)
83.31 (3.28")
38.1
(1.5")
73.0 (2.874")**
7.11 (.280")
38.1
(1.5")
Option Codes
L = RoHS + HF
(Only applies to 251 Series)
6.35 (.25")
tape
F
L
6.35 (.25")
tape
5.0 (.197")
1A
2.61 (.103")
MAX
F
L
1A
Wire Diameter:
0.64 (.025") for 0.62-10.0 amp,
0.81 (.032") for 15 amp
Packaging
Packaging Option
*T1: 52.4mm (2.062") Tape and Reel
**T3: 73mm (2.874') Tape and Reel
Packaging Specification
EIA 296
EIA 296
Quantity &
Packaging Code
Please refer to available quantities
above in "Part Numbering System”
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.
© 2014 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: 03/10/14
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