Radial Lead Fuses
MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series
272/273/274/278/279 Series,
MICRO™ Very Fast-Acting Fuse
QPL
Description
Developed originally for the U.S. Space Program,
MICRO™ fuse provides reliability in a compact design.
The MICRO™ fuse is available in plug–in or radial lead
styles and a complete range of ampere ratings from
1/500 to 5A to suit a wide variety of design needs.
Features
Military grade available
High breaking capacity
Clear cover option to view
fuse element status
Agency Approvals
Applications
Agency
Agency File Number
Ampere Range
Available from very low
ampere of 2mA to 5A
Plug-in with short or long
leads option
E10480
LR 29862
2mA - 5A
2mA - 5A
2mA - 5A
Printed circuit boards
and similar equipment
Electrical Characteristics
% of Ampere
Rating
100%
200%
Ampere Rating
1/500–5
1/500–3/10
4/10-5
Electronic components
QPL
FM02
Opening Time
4 Hours,
Min.
5 Seconds,
Max.
2 Seconds,
Max.
Electrical Characteristics
Ampere
Rating
(A)
.002
.005
.010
.015
.031
.050
.062
.100
.125
.200
.250
.300
.400
.500
.600
.700
.750
.800
1.00
01.5
2.00
3.00
4.00
5.00
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,
/278.html or /279.html for current information.
Amp Code
(for all
above
series)
.002
.005
.010
.015
.031
.050
.062
.100
.125
.200
.250
.300
.400
.500
.600
.700
.750
.800
001.
01.5
002.
003.
004.
005.
Max
Voltage
Rating
(V)
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
125
Interrupting
Rating
10,000 amperes at
125 VAC/VDC.
Nominal
Cold
Resistance
(Ohms)
2200
280
80.0
44.0
16.0
3.20
2.32
1.25
1.0
2.30
1.75
1.25
0.227
0.167
0.430
0.324
0.293
0.271
0.0880
0.0578
0.0425
0.0275
0.0202
0.0156
Nominal
Melting
I
2
t (A
2
sec)
0.00000000845
0.00000000810
0.000000462
0.00000123
0.00000810
0.0000666
0.000115
0.000385
0.000691
0.00409
0.00640
0.00945
0.0251
0.0716
0.0411
0.0710
0.0900
0.113
0.0648
0.160
0.300
0.759
1.38
2.21
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Agency Approvals
QPL
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
131
Revised: January 7, 2009
272/273/274/278/279 Series
272-4/278-9
Radial Lead Fuses
Introduction to Circuit Protection
Transientology
MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series
Temperature Rerating Curve
Average Time Current Curves
1/200 A
1/100 A
1/64 A
100
10
TIME IN SECONDS
1
0.1
0.01
0.001
0.005
1/2 A
3/4 A
1A
1 1/2 A
2A
3A
4A
5A
1/32 A
1/16 A
1/8 A
1/4 A
0.01
1
0.1
CURRENT IN AMPERES
10
100
Soldering Parameters - Wave Soldering
300
Recommended Process Parameters:
Wave Parameter
Preheat:
(Depends on Flux Activation Temperature)
(Typical Industry Recommendation)
Temperature
(°C) - Measured on bottom side of board
280
260
240
220
200
180
160
140
120
100
80
60
40
20
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
10
20
30
40
50
60
70
80
90
0
0
Lead-Free Recommendation
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-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.
Time
(Seconds)
Preheat
Time
Dwell
Time
Cooling
Time
272/273/274/278/279 Series
132
Revised: January 7, 2009
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,
/278.html or /279.html for current information.
Radial Lead Fuses
MICRO™ > Very Fast-Acting > 272/273/274/278/279 Series
Product Characteristics
273 and 279: –55ºC to +85ºC;
272 and 278: –55ºC to +125ºC
273 Series is available in CSA LR
29862. Military QPL type (FM02).
To order, change 273 to 274.
272 and 278 series cap:
Nickel Plated Brass
273, 274 and 279 series cap:
Mirror polished Polycarbonate
Base: R-4 Ryton
Pins: Tin Plated Copper
Product Marking
Current and voltage ratings stamped
on cap
Dimensions
272 000 Series
(Short Lead, Metal Cap)
5.97
(.235")
7.30
(.29")
(.17")
Operating Temperature:
4.32
Fuses to MIL SPEC
2.54 (.10")
278 000 Series
(Long Lead, Metal Cap)
5.97
(.235")
7.30
(.29")
25.4 (1.0")
2.54 (.10")
Materials
273 000 and 274 000 Series
Part Numbering System
(Short Lead, Clear Plastic Cap)
6.35
(.25")
8.89
(.35")
(.17")
4.32
0273 xxxx V
Series
Amp. Code
Refer to Amp Code column of
Electrical Characteristics Table
2.54 (.10")
279 000 Series
(Long Lead, Clear Plastic Cap)
6.35
(.25")
8.89
(.35")
25.4 (1.0")
2.54 (.10")
Packaging Code
V=5
H = 100
NOTE: Amperage and voltage rating stamped on cap.
Leads are tin plated copper; .025" diameter.
Packaging
Packaging Option
Bulk
Bulk
Packaging Specification
N/A
N/A
Quantity
5
100
Quantity &
Packaging Code
V
H
© 2009 Littelfuse, Inc.
Specifications are subject to change without notice.
Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,
/278.html or /279.html for current information.
133
Revised: January 7, 2009
272/273/274/278/279 Series
272-4/278-9
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