TE Connectivity FWFU Series Fusible Wire Wound Fixed Resistor
Introduction
TE Connectivity (TE)'s Fusible Wire Wound Fixed (FWFU) Resistors are a special type of resistor that also act as a safety fuse. They allow current to flow normally but break the circuit when the current exceeds a safe level, protecting electronic devices from damage. These resistors are commonly used in power supplies, chargers, and household appliances to help prevent overheating and short circuits. Unlike traditional fuses, they provide some resistance before they "blow," making them useful for controlling inrush current.
Features
- UL recognised (UL1412): UL file no.
- Power up to 7 watts
- RoHS compliant with no exemptions
- Moisture sensitivity level-MSL1
- Flame resistant coating meets UL 94 VO requirements
- Fusing time up to 120s
Applications
- LED lighting/LED Drivers
- EV chargers
- Power supply
- Test measurement equipment
- Surge protection and voltage divider
- Energy meter
Electrical Characteristics
| Size | Type | Rated Power @70°C Watts | Resistance tolerance | Ohmic value Min (Ω) | Ohmic value Max (Ω) | Dielectric withstand Voltage | Max working voltage | Max overload voltage | Operating temperature | Climatic category | Net weight (mg) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Standard Size | FWFU 1W | 1 | ±5% | R47 | 240R | 1000VAC | RCWV = √(P x R) | 2.5 √(P x R) | -55°C - 155°C | 55/155/42 | 630 |
| FWFU 2W | 2 | 990 | |||||||||
| FWFU 3W | 3 | 1620 | |||||||||
| FWFU 5W | 5 | 10R | 47R | 2590 | |||||||
| FWFU 7W | 7 | 240R | 3940 | ||||||||
| Small Size | FWFU 1WSS | 1 | ±5% | R47 | 1000VAC | RCWV = √(P x R) | 2.5 √(P x R) | -55°C - 155°C | 55/155/42 | 185 | |
| FWFU 1WS | 1 | 350 | |||||||||
| FWFU 2WS | 2 | 630 | |||||||||
| FWFU 3WS | 3 | 990 |
Power Rating
Resistors shall have a power rating based on continuous full load operation at an ambient temperature of 70°C. For temperature in excess of 70°C, the load shall be derated as shown on the derating curve.
Voltage Rating
Resistors shall have a rated direct-current (DC) continuous working voltage or an approximate sine-wave root-mean-square (RMS) alternating-current (AC) continuous working voltage at commercial line frequency and waveform corresponding to the power rating, as determined from the following formula:
RCWV = √(P x R)
Where: RCWV = Rated DC or RMS AC continuous working voltage at commercial-line frequency and waveform (volt)
P = Power Rating (watt)
R = Nominal Resistance (ohm)
In no case shall the rated DC or RMS AC continuous working voltage be greater than the applicable maximum value.
Derating Curve
A graph shows the percentage of rated load versus ambient temperature (°C). The curve starts at 100% rated load at 70°C and decreases linearly to 0% rated load at 275°C.
Heat Rise Chart
A graph shows temperature rise (°C) versus percentage of rated load (%). Multiple lines represent different resistor types (e.g., 1W-SS, 1W-S, 2W-S, 3W-S, 1W, 2W, 3W, 5W, 7W).
Thermal Resistance
A graph shows thermal resistance (°C/W) versus rated load (%). Multiple lines represent different resistor types.
Fusing Graph
A graph shows fusing time (s) versus multiplier of power rated. It illustrates the time it takes for the resistor to blow under different overload conditions.
Construction
Diagram showing the construction of the resistor with numbered parts:
- 1. Basic Body: Rod Type Ceramics
- 2. Resistance Wire: Resistance Wire Alloy
- 3. End Cap: Steel (tin plated iron surface)
- 4. Lead Wire: Annealed Copper wire with a tin matte finish
- 5. Connection: Lead wire to end cap attachment method: welded
- 6. Coating: Insulated and non-flame paint (colour: green)
- 7. Colour Code: Non-flame epoxy resin
Performance Characteristics
| Characteristics | Limits | Test Methods (JIS C 5201-1) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DC Resistance | Must be within the specified tolerance | The limit of error of measuring apparatus shall not exceed allowable range or 5% of the resistance tolerance (Sub-clause 4.5) | |||||||||||||||
| Dielectric withstanding voltage | No evidence of flashover, mechanical damage, arcing or insulation break down | Resistors shall be clamped in the trough of a 90° metallic V-block or foil method use a metal foil shall be wrapped closely around the body of the resistor. After that shall be tested at AC potential respectively specified in the electrical characteristic, for 60 +10/-0 secs. (Sub-clause 4.7) | |||||||||||||||
| Temperature coefficient | <20Ω : ± 400 PPM/°C ≥20Ω : ± 300 PPM/°C |
Natural resistance change per temp. degree centigrade. R2-R1X10 (PPM/°C) R1(t2-t1) R1: Resistance value at room temperature (t1) R2: Resistance value at room temperature plus 100°C (t2) (Sub-clause 4.8) |
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| Short time overload | Resistance change rate is ± (2% + 0.05Ω) Max. with no evidence of mechanical damage | Permanent resistance change after the application of a potential of 2.5 times RCWV or Max. overload voltage, whichever is lesser for 5 seconds (Sub-clause 4.13) | |||||||||||||||
| Terminal strength | No evidence of mechanical damage | Direct load: Resistance to a 2.5kgs direct load for 10 secs. In the direction of the longitudinal axis of the terminal leads Twist test: Terminal leads shall be bent through 90° at a point of about 6mm from the body of the resistor and shall be rotated through 360° about the original axis of the bent terminal in alternating direction for a total of 3 rotations (Sub-clause 4.16) |
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| Solderability | 95% coverage Min. | The area covered with a new, smooth, clean, shiny and continuous surface free from concentrated pinholes. Test temp. of solder: 245°C ±3°C Dwell time in solder: 2~3 seconds (Sub-clause 4.17) |
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| Soldering temp. reference | Electrical characteristics shall be satisfied. Without distinct deformation in appearance. (95% coverage Min.) | The leads immersed into solder bath to 3.2 to 4.8mm. from the body. Permanent resistance change shall be checked. Wave soldering condition: (2 cycles Max.) Pre-heat: 100~120°C, 30±5 sec. Suggestion solder temp: 235~255°C, 10 sec. (Max.) Peak temp: 260°C Hand soldering condition: Hand soldering bit temp: 380±10°C Dwell time in solder: 3 +1/-0 sec. |
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| Resistance to soldering heat | Resistance change rate is ±(1%+0.05Ω) Max. with no evidence of mechanical damage | Permanent resistance change when leads immersed to 3.2mm to 4.8mm from the body in 350°C ± 10°C solder for 3 ± 0.5 seconds. (Sub-clause 4.18) | |||||||||||||||
| Temperature cycling | Resistance change rate is ± (2% + 0.05Ω) Max. with no evidence of mechanical damage | Resistance change after continuous 100 cycles for duty shown below:
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| Load life in humidity | Resistance change rate is ±(5% + 0.05Ω) Max. with no evidence of mechanical damage | Resistance change after 1,000 hours (1.5 hours "on", 0.5 hour "off") at RCWV in a humidity test chamber controlled at 40°C ± 2°C and 90 to 95% relative humidity (Sub-clause 4.24.2.1) | |||||||||||||||
| Load life | Resistance change rate is ±(5% + 0.05Ω) Max. with no evidence of mechanical damage | Permanent resistance change after 1,000 hours operating at RCWV with duty cycle of (1.5 hours "on", 0.5 "hour off") at 70°C ± 2°C ambient (Sub-clause 4.25.1) | |||||||||||||||
| Flammability | No ignition of the tissue paper or scorching of the pine wood board | V-0 or V-1 are acceptable. Electrical test not required (UL 94 rating) | |||||||||||||||
| Fusing test | Resistance should be opened (The resistance value is over than 50 times from before test value) follow fusing curve condition | Magnification of power Fusing Fusing time(s) 35 times 120s (max) A graph shows fusing time (s) versus multiplier of power rated. |
Dimensions (Unit:mm)
Diagram showing resistor dimensions with labels D (Max), L (Max), d ± 0.05, H ± 3. A table lists these dimensions for various FWFU types.
| Type | D (Max) | L (Max) | d ± 0.05 | H ± 3 |
|---|---|---|---|---|
| FWFU 1W | 5.0 | 12.0 | 0.70 | 28 |
| FWFU 2W | 5.5 | 16.0 | 0.70 | 28 |
| FWFU 3W | 6.5 | 17.5 | 0.75 | 28 |
| FWFU 5W | 8.0 | 20.0 | 0.75 | 38 |
| FWFU 7W | 8.5 | 25.0 | 0.75 | 38 |
| FWFU 1WSS | 3.0 | 8.5 | 0.54 | 28 |
| FWFU 1WS | 4.3 | 9.0 | 0.6 | 28 |
| FWFU 2WS | 5.0 | 12.0 | 0.7 | 28 |
| FWFU 3WS | 5.5 | 16.0 | 0.7 | 28 |
Pulse Limit Power
A graph shows pulse limit power (W) versus added time (s) on a logarithmic scale. Multiple lines represent different resistor types.
Pulse Characteristics (Repeat)
Diagrams illustrate different pulse waveforms: discharge waveform of a capacitor, sine curve, triangular wave, and special wave. Formulas are provided for calculating pulse limit power and related parameters.
Pp = K*P*T/ τ
Vp = √(K*P*R*T/ τ)
Reference to the right about a fixed number of Vp max:
- T/τ >100 → T/τ =100
- P < Pn → P stands for Pn (Vp < VR → VR stands for Vp)
- Added voltage ≤ Vp max
- Pn or VR is referent value
Condition: Pulse added time = 1000h
Resistance change = ±5%
Room temperature
A table shows the K factor for FWFU types.
| Type | Power | K | Vp max |
|---|---|---|---|
| FWFU | All power rate | 0.70 | 500 |
1.2/50μS Lightning Surge (IEC61000-4-5)
A graph shows peak voltage (V) versus resistance values (Ω) on a logarithmic scale, illustrating the resistor's performance under lightning surge conditions. Multiple lines represent different resistor types.
Painting Method
Diagram showing the resistor with labels for welding point, lead wire, coated-length, and the blank uncoated area (D = Resistor body diameter). It states that the welding point, terminal, and lead wire are permissible to be exposed without the outer coated cover, within 1/2 of the cap diameter.
Marking
Resistors are marked with colour coding according to JIS C 0802. The marking includes the 1st significant figure, 2nd significant figure, multiplier, tolerance, and identified color code for UL.
Labels
Labels include the following items:
- TYCO Pn: 5-2176794-7
- DESC: FWFU 5W ± 5% 100 R
- QTY: 1000 Pcs.
- LOT: 5220228 RT008-04
- REF: TEST ROHS 3 (2015/863/EU)
- TE connectivity logo and DC: 2522
- (1) Type and style, resistance tolerance, nominal resistance
- (2) Quantity
- (3) Lot number
Packaging
Taping Dimensions (mm)
Diagram showing taping dimensions with labels P, L1, L2, T, Z, R, t, S. A table lists these dimensions for various FWFU types and styles (PT-52, PT-64).
Tape in Box Packaging (mm) - Ammo Pack
Diagram of an ammo pack with labels A, B, C. A table lists dimensions (C ±5, A ±5, B ±5) and Quantity Per Box (pcs) for various FWFU types and styles.
Tape on Reel Packaging (mm)
Diagram of a reel with labels for leader, resistor, paper, cylinder, bandolier, and flange. A table lists Across Flange (A) and Quantity Per Reel for various FWFU types and styles.
Box Packing (Plastic Case) (mm)
Diagrams show box packing and bulk in inner box packing. A table lists dimensions (C ±5, A ±5, B ±5 for outer box and L ±5, W ±5, H ±5 for inner box) and Quantity Per Case/Box (pcs) for FWFU 5W and FWFU 7W.
Environmental Related Substance
This product complies with EU RoHS directive, EU PAHs directive, EU PFOS directive, and Halogen free. Ozone depleting substances are not used in the manufacturing process. The product is not manufactured using Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), Hydrobromofluorocarbons (HBFCs) or other ozone depleting substances.
Storage Condition
The performance of these products, including solderability, is guaranteed for a year from the date of arrival, provided they remain packed and stored at 25°C ± 10°C and 60%RH ± 10%RH, in a chemical and dust-free atmosphere. Avoid storing in salty air, air with high concentration of corrosive gas (e.g., Cl₂, H₂S, NH₃, SO₂, NO₂), or in direct sunlight, as this may deteriorate electrical performance, solderability, and packaging materials.
Ordering Information
Common Part: FWFU (Fusible Wire Wound Resistor UL Approved)
Part Number structure example: FWFU 1W 6R8 J
Breakdown:
- FWFU: Common Part
- Power Rating: Standard Size (1W, 2W, 3W, 5W, 7W) and Small Size (1WSS, 1WS, 2WS, 3WS)
- Tolerance: J (5%)
- Resistance Value: R10 (100 mohm), 1R0 (1 ohm), 10R (10 ohm), 100R (100 ohm)
