Radial Lead Fuses
MICRO > Very Fast-Acting > 272/273/274/278/279 Series
QPL
272/273/274/278/279 Series, MICRO Very Fast-Acting Fuse
Description
Developed originally for the U.S. Space Program,
MICRO fuse provides reliability in a compact design.
The MICRO fuse is available in plugin 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
t Military grade available t Available from very low
ampere of 2mA to 5A
t High breaking capacity
t Plug-in with short or long
t Clear cover option to view
leads option
fuse element status
Agency Approvals
Applications
Agency Agency File Number Ampere Range
t Printed circuit boards t Electronic components
E10480 2mA - 5A
and similar equipment
LR 29862 2mA - 5A
Electrical Characteristics
FM02 2mA - 5A
QPL
% of Ampere
Ampere Rating Opening Time
Rating
100% 1/5005 4 Hours, Min.
1/5003/10 5 Seconds, Max.
200%
4/10-5 2 Seconds, Max.
Electrical Characteristics
Amp Code Max Nominal Agency Approvals
Ampere Nominal
(for all Voltage Interrupting Cold
Rating Melting
above Rating Rating Resistance
2 2 QPL
(A) I t (A sec)
series) (V) (Ohms)
.002 .002 125 2200 0.00000000845 XXX
XXX
.005 .005 125 280 0.00000000810
.010 .010 125 80.0 0.000000462 XXX
.015 .015 125 44.0 0.00000123 XXX
.031 .031 125 16.0 0.00000810 XXX
XXX
.050 .050 125 3.20 0.0000666
.062 .062 125 2.32 0.000115 XXX
.100 .100 125 1.25 0.000385 XXX
.125 .125 125 1.0 0.000691 XXX
XXX
.200 .200 125 2.30 0.00409
.250 .250 125 1.75 0.00640 XXX
10,000 amperes at
.300 .300 125 1.25 0.00945 XXX
125 VAC/VDC.
.400 .400 125 0.227 0.0251 XXX
XXX
.500 .500 125 0.167 0.0716
XXX
.600 .600 125 0.430 0.0411
.700 .700 125 0.324 0.0710 XXX
.750 .750 125 0.293 0.0900 XXX
XXX
.800 .800 125 0.271 0.113
XXX
1.00 001. 125 0.0880 0.0648
01.5 01.5 125 0.0578 0.160 XXX
XXX
2.00 002. 125 0.0425 0.300
3.00 003. 125 0.0275 0.759 XXX
4.00 004. 125 0.0202 1.38 XXX
5.00 005. 125 0.0156 2.21 XXX
2009 Littelfuse, Inc.
272/273/274/278/279 Series
131
Specications are subject to change without notice.
Revised: January 7, 2009
Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,
/278.html or /279.html for current information.
272-4/278-9Radial Lead Fuses
IntrIntroduction toduction too Cir Circuit Prcuit Prototectionection
Transientology
MICRO > Very Fast-Acting > 272/273/274/278/279 Series
Temperature Rerating Curve Average Time Current Curves
100
10
1
0.1
0.01
0.001
0.005 0.01 1 10 100
0.1
CURRENT IN AMPERES
Soldering Parameters - Wave Soldering
300
Recommended Process Parameters:
280
260
Wave Parameter Lead-Free Recommendation
240
220 Preheat:
(Typical Industry Recommendation)
200 (Depends on Flux Activation Temperature)
180
Temperature Minimum:
100 C
160
Temperature Maximum:
150 C
140
120
Preheat Time: 60-180 seconds
100
Solder Pot Temperature: 260 C Maximum
80
60
Solder Dwell Time: 2-5 seconds
40
20
0
Recommended Hand-Solder Parameters:
Time (Seconds)
Solder Iron Temperature: 350 C +/- 5C
Preheat Time Cooling Time
Dwell Time
Heating Time: 5 seconds max.
Note: These devices are not recommended for IR or
Convection Reow process.
2009 Littelfuse, Inc.
272/273/274/278/279 Series
132
Specications are subject to change without notice.
Revised: January 7, 2009
Please refer to www.littelfuse.com/series/272.html, /273.html, /274.html,
/278.html or /279.html for current information.
Temperature (C) - Measured on bottom side of board
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 IN SECONDS
1/200 A
1/100 A
1/64 A
1/32 A
1/16 A
1/8 A
1/4 A
1/2 A
3/4 A
1 A
1 1/2 A
2 A
3 A
4 A
5 A