WFF [TTELEC]
Fast Fusible Metal Film Resistors; 快易熔金属膜电阻器型号: | WFF |
厂家: | TT Electronics |
描述: | Fast Fusible Metal Film Resistors |
文件: | 总3页 (文件大小:90K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Fast Fusible Metal
Film Resistors
Welwyn Components
WFF Series
Low power fusing
•
Predictable fusing characteristics
•
Flameproof protection
•
Electrical Data
1
WFF /4
WFF1/2
0.5
WFF1
1
Power rating at 70˚ C
Resistance range
watts
ohms
volts
0.25
0R1 - 10K
250
0R10 - 27K
350
0R2 - 1K5
350
Limiting element voltage
TCR
ppm/˚ C
%
250
Resistance tolerance
Standard values
5
E24 preferred
120
Thermal impedance
Ambient temperature range
˚ C/watt
˚ C
150
100
-55 to 155
Physical Data
Dimensions (mm) & Weight (g)
Type
L
D
f
d
PCB
Min.
bend
radius
Wt.
max
max
min
nom
mounting
centres
nom
d
WFF1/4
WFF1/2
WFF1
6.2
9.0
2.5
3.4
4.2
21.0
19.6
17.8
0.6
0.8
0.8
10.2
12.7
18.4
0.6
1.2
1.2
0.3
0.6
0.9
D
L
f
12.5
Construction
Marking
The metal film is deposited on a high purity ceramic rod. End
caps are force fitted and termination wires welded to the
caps. The resistive film is adjusted to the required value by a
special helical cut. A fuse aid coating is then applied. Finally a
cement protection is applied to the resistor body prior to
marking with indelible ink.
Resistors are colour coded with 5 bands. Four of the bands
are used to indicate values and tolerance, with IEC 62 colours
being used. A fifth yellow band denotes constant voltage
fusibility.
Solvent Resistance
The body protection and marking are resistant to all normal
Terminations
industrial cleaning solvents suitable for printed circuits.
Material
Solder-coated copper wire.
Flammability
Strength
The terminations meet the requirements of
IEC68.2.21.
The resistors will not burn or emit incandescent particles
under any condition of applied temperature or power
overload.
Solderability The terminations meet the requirements of
IEC 115-1 Clause 4.17.3.2.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Issue E · 01.07
161
Fast Fusible Metal
Film Resistors
WFF Series
Welwyn Components
Performance Data
Maximum
Load: 1000 hrs at 70˚ C
R%
R%
3
Shelf life: 12 months at room temperature
Derating from rated power at 70˚ C
Temperature rapid change
2
zero at 155˚ C
0.5
R%
R%
Resistance to solder heat
0.5
Pulse Handling Graphs
Graph 2
1.2/50μS Pulse Withstand
10/700μS Pulse Withstand
Graph 1
10000
10000
1000
1000
100
10
WFF 1/4
WFF 1/4
100
10
WFF 1/2
WFF 1
WFF 1/2
WFF 1
10
100
1000
10000
100000
10
100
1000
10000
100000
Value (OHMS)
Value (OHMS)
Above tests carried out in accordance with IEC 115.1. Change of value after test 1%
Maximum peak pulse voltage
as a function of pulse duration (ti)
Graph 3
10000
Maximum peak pulse power
as a function of pulse duration (ti)
Graph 4
100
WFF 1/4
WFF 1/2
WFF 1
10
1
1000
WFF 1/4
WFF 1/2
WFF 1
100
0.0001
0
0.0010
0.0100
0.1000
1.0000
0.0001
0.0010
0.0100
0.1000
1.0000
ti (s)
ti (s)
Figure 1
Test Method (for graph 3 and 4)
The resistor is subject to 10,000 pulses as shown in figure
(1). Maximum resistance change due to test will not
exceed 1%. Maximum pulse voltages are detailed in graph
3 above.
For any combination of power and pulse length (ti). tp is
determined by the need to ensure that the average power
does not exceed the rated power.
Time (secs)
t
t
i
tp =
Applied Pulse Power
Rated Power
p
x ti
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
IssueE · 01.07
162
Fast Fusible Metal
Film Resistors
WFF Series
Welwyn Components
Packaging
All resistors are supplied tape packed ready for loading
onto automatic sequencing and insertion machines.
The standard taping method and critical dimensions are
shown in figure 2.
Lead Formed resistors can also be supplied. Standard
options of Lancet, Radial and Goalpost forming are shown
in Lead Form Information section.
Figure 2
52
Body Location f
1.4 m
Standard Quantities Per Package
Type
WFF1/4
WFF1/2
WFF1
Large ammo pack
5000
2500
1500
*Contact Welwyn for R10 - 1R0 fusing data
Fusing (Constant voltage)
After fusing the final resistance value will be 50 times the
initial value.
© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com
Isue E ·01.07
163
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