Bussmann
®
SMD TRON
®
Surface Mount Fuses
For .170” x .294” (4.32mm x 7.47mm) Fuses
Time-Current Characteristic CurvesÐAverage Melt
(Full Size Curves Available)
250mA
375mA
500mA
750mA
AMPERE RATING
12.5A
1A
1.5A
2A
2.5A
3A
3.5A
5A
7A
10A
SFT
R
10
Catalog Symbol:
SFT
Characteristics:
Fast-Acting, Current-Limiting
Construction:
Solid Matrix
Dimensional Data
.29" (± .015)
.17" (± .015)
(4.32 mm) (± .006)
.12" (± .015)
(3.05 mm) (± .006)
TIME IN SECONDS
.09" (± .015)
(2.29 mm) (± .006)
(7.47 mm) (± .006)
1
BUSS
SFT
5A
125V
A123
.1
.05"
(1.27 mm)
*Packaging & Ordering Information:
SFT
Product
Symbol
Package Code
TR/
500 pcs., on a 7” reel, 16mm tape width.
TR1/
2000 pcs., on a 13” reel, 16mm tape width.
TR2/
500 pcs., on a 7” reel, 12mm tape width.
TR3/
2500 pcs., on a 13” reel, 12mm tape width.
Weight
=
.6 lbs/500
*See page 2.
(See Table)
Rated Current
1
CURRENT IN AMPERES
Time-Current Characteristics:
Rated
Current
0-10
Percent of Rating
100%
4 hrs. (min)
250%
5 sec. (max)
Electrical Characteristics
Typical Voltage
Agency**
Rated
Interrupting
Pre-arcing
Typical Total Clearing
3
Drop
2
Volts at
Approvals
Rated
Voltage
Rating
1
I
2
T (A
2
sec)
I
2
T (A
2
sec)
100% Rated
5
Current
AC (Max.)
DC (Max.)
AC
DC
AC
DC
AC
DC
Current
63mA
125V
125V
50A
300A
•
•
125mA
125V
125V
50A
300A
•
•
250mA
125V
125V
50A
300A
7.49 x 10
-5
5.1 x 10
-6
2.0 x 10
-4
6.29 x 10
-6
.8
•
•
375mA
125V
125V
50A
300A
3.17 x 10
-4
2.18 x 10
-5
4.18 x 10
-4
2.67 x 10
-5
.75
•
•
500mA
125V
125V
50A
300A
4.46 x 10
-4
3.8 x 10
-5
5.74 x 10
-4
4.63 x 10
-5
.66
•
•
750mA
125V
125V
50A
300A
1.72 x 10
-3
2.27 x 10
-4
2.59 x 10
-3
2.77 x 10
-4
.525
•
•
1
125V
125V
50A
300A
.0099
.0069
.0114
.0076
.12
•
•
1.5
125V
125V
50A
300A
.0302
.0204
.0345
.0246
.20
•
•
2
125V
125V
50A
300A
.0784
.0651
.0891
.0811
.170
•
•
2.5
125V
125V
50A
300A
.1775
.1390
.2383
.1574
.145
•
•
3
125V
125V
50A
300A
.3355
.2419
.4359
.2664
.130
•
•
3.5
125V
125V
50A
300A
.4980
.3812
.6355
.4696
.155
•
•
4
125V
125V
50A
300A
.8855
.6785
1.0740
.7829
.135
•
•
5
125V
125V
50A
300A
1.7264
1.2912
2.3779
1.3556
.125
•
•
7.0A
60V
90V
50A
300A
1.64
.518
1.97
.573
.114
•
•
10.0A
60V
90V
50A
300A
3.79
1.06
3.92
1.67
.130
•
•
12.5A
48V
60V
50A
300A
15
4.04
20
4.28
.090
•
**Approvals: UL Recognition, Std. 248-14, Guide #JDYX2, File #E19180; CSA Certification, C22.2 No. 248.14, Class #1422-01, File #53787.
NOTE: SFT 12.5A is UL recognized on AC Only.
1. Interrupting ratings were measured at 100% power factor on AC, and a time constant less than 1ms on DC.
2. Voltage drop was measured at 25°C ± 3°C ambient temperature at rated current with device mounted on a circuit trace.
3. I
2
t measured at 50 amp, 125 VAC, .95PF, random closing angle; 300 amps, 125 VDC, TC<1ms.
4. Electrical characteristics for 12.5 amp to be determined.
5. Device designed to carry 125% of rated current for one hour minimum. An operating current of 80% or less of rated current is recommended, with further derating
required at elevated ambient temperatures.
CE logo denotes compliance with European Union Low Voltage Directive
(50-1000 VAC, 75-1500 VDC). Refer to BIF document #8002 or contact
Bussmann Application Engineering at 314-527-1270 for more information.
U.R.
CSA
10
.01
12-28-98
SB98107
Rev. A
Form No. SFT
Page 1 of 2
BIF Doc #2005
Bussmann
®
SMD TRON
®
Surface Mount Fuses
For .170” x .294” (4.32mm x 7.47mm) Fuses
1.0 Materials
Body Material:
Thermoplastic, with a rating of 94V-O as defined by U.L.
Standard 94. Material has an oxygen index of 53% per ASTM D2863-77.
Lead Material:
Base–Copper.
Barrier–Nickel (50-100 micro inches).
Finish–Electroplated Tin (400-500 micro inches with a
2-10% lead content).
2.0 Markings
Body shall be permanently and legibly marked with BUSS
®
, catalog symbol,
ampere rating, voltage rating and date code. Markings will not become illegible
or discolored when the parts are subjected to solvents normally used to remove
solder/flux, fingerprints, and other contaminants from printed circuit boards, as
tested per MIL-STD-202, Method 215F.
3.0 Trace Geometry Considerations
Trace geometry can affect fuse performance and should be considered when
applying any subminiature fuse. Figures 1 and 2 detail the trace geometry used
in generating this specification. Suitable trace geometry for a particular applica-
tion depends on fuse rating, current flow, and ambient temperature. Final deter-
mination of suitability for a specific application should be based on empirical
testing with all parameters involved. Printed circuit board is .096 inches thick,
epoxy glass with 1 ounce copper foil, coated with 300 micro inches of 60/40 tin
lead solder.
Detail A
SFT
R
Terminal Secureness.
The fuse terminals shall not distort, and the fuse body
will not chip or crack when the fuse is placed on a printed circuit board and a
vertical downward force of 1/2 kilograms is applied to the top of the fuse for 10
seconds.
6.0 Packaging
All unit packaging material will be manufactured from static inhibiting materials.
Tape and reel packaging will comply with EIA Std 481-2. Tape width shall be
16mm and reel diameter 7 inches or 13 inches.
Packaging Code
TR/ 500 on a 7" reel, 16mm tape width
TR1/ 2000 on a 13" reel, 16mm tape width
.14"
.06" Dia.
A
.08"
.16"
.07"
.3"
.63"
Embossed carrier tape which
conforms to the EIA Standards
EIA481-2.
Carrier material black
conductive polystyrene,
Non-Conductive Tape Material.
.31"
.01"
A
.19"
.32"
Figure 4
7.0 Load Cycling
Load cycling of the SMD TRON
®
was performed to observe the stability of the
resistances and voltage drops for cycling applications. Through measurement
of initial and final resistances, an assessment of the reliability of the fuse can be
predicted.
Test Conditions.
A duty cycle of 60 seconds on at rated current and 60 sec-
onds off to make a total period of 120 seconds.
Other circuit parameters were:
Amplitude – 100% rated current
Rise Time – 36.8 microseconds
Ripple Average –15.9mA
System Voltage – 55 volts
Test Criteria.
The fuse must complete 200,000 cycles without failure, then
resistance and voltage drop measurements are compared to initial measure-
ments, which cannot change by more than 5%.
Test Data:
Average Initial Resistance: 21.11 milli ohms
Average Final Resistance: 20.57 milli ohms
% Change: –2.55%
SFT Voltage Drop as a Percent of Rated Current (Typical)
.8
.7
.6
Voltage Drop
.5
.4
.3
.2
.1
0
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Rated Current
.2
SFT-1.5
SFT-2
.18
SFT-3.5
.16
SFT-2.5
SFT-4
.14
SFT-3
.12
SFT-10
SFT-5
.1
SFT-1
.08
SFT-7
.06
.04
.02
0
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Rated Current
Detail A
.350"
.100"
000
2.550"
2.495"
2.305"
2.250"
4.800"
4.550"
.250"
000
.055"
.060"
.114"
Figure 1
Figure 2
Note:
Smaller than recommended trace width may
affect the fuse performance by providing additional heat and reducing carrying
capacity of the fuse.
4.0 Thermal Withstand Capability
Infrared Exposure.
When the device is exposed to the time-temperature profile
detailed in Figure 3, the resistance of the device will not change by more than
5%, as measured after the device has dwelled at room temperature for at least
one hour.
250°C
230°C
175°C
SFT-.25
SFT-.5
SFT-.375
SFT-.75
25°C
2 min.
3.5 min.
2 min.
25°C
Figure 3
IR
Time-Temperature Profile
Vapor Phase Exposure.
When the device is exposed for ten minutes to the
vapor produced by liquid fluorinert FC-5312 at 218°C, the resistance of the
device will not change by more than 5%, as measured after the device has
dwelled at room temperature for at least one hour.
Resistance to Soldering Heat.
MIL-STD-202F, Method B. When device is
immersed in a 260°C soldering pot for 10 seconds, the resistance of the device
will not change by more than 5% as measured after the device has dwelled at
room temperature for at least one hour.
*Better Solderability.
To eliminate solder ball extrusion and to provide
improved solderability in formed areas of leads, order part number
SFT-1J0367-amp. For 63mA - 10A fuses.
5.0 Mechanical Characteristics
Mechanical Shock.
Fuse base shall not chip or crack when dropped from a
height of 48" onto a concrete surface.
Vibration.
The fuse resistance shall return to within 10% of the original value
when the fuse is subjected to a frequency range cycle of one minute in each of
the three mutually perpendicular directions having a vibration amplitude of .06
inches peak to peak at a frequency of 10-55Hz. per MIL-STD-202F, Method 204
Condition A.
12-28-98
SB98107
Rev. A
The only controlled copy of this BIF document is the electronic read-only version located on the Bussmann Network Drive. All other
copies of this BIF document are by definition uncontrolled. This bulletin is intended to clearly present comprehensive product data
and provide technical information that will help the end user with design applications. Bussmann reserves the right, without notice,
to change design or construction of any products and to discontinue or limit distribution of any products. Bussmann also reserves
the right to change or update, without notice, any technical information contained in this bulletin. Once a product has been selected,
it should be tested by the user in all possible applications.
Voltage Drop
Form No. SFT
Page 2 of 2
BIF Doc #2005
PCB Design
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