Part A
0451003.MRL
Компания Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 7735 ПКС
- Series
- Защитники
Replacement verdict
Compatible functional replacement candidate
The 0451003.MRL and 0451005.MRL are both fast-acting surface-mount fuses from the Littelfuse 451 series, sharing identical package, voltage rating, and interrupting capacity. The primary distinction is the current rating, with the 0451003.MRL rated at 3A and the 0451005.MRL rated at 5A. Because the current rating differs, the 0451005.MRL should not be used as a direct substitute for the 0451003.MRL in circuits designed around a 3A protection threshold. Verify the application's steady-state and inrush current requirements before considering either part as a replacement for the other.
Current Rating
Validation required
Package Type
High match
Voltage Rating
High match
Breaking Capacity
High match
Parts at a glance
Part B
0451005.MRL
Компания Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 6135 ПКС
- Package
- 2-SMD
- Series
- Защитники
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 0451003.MRL | 0451005.MRL | Why it matters |
|---|---|---|---|
| Current Rating | 3 A | 5 A | Determines the maximum continuous current the fuse can carry without opening; a direct functional difference affecting circuit protection sizing. |
| Voltage Rating (DC) | 125 V | 125 V | Specifies the maximum DC voltage the fuse can safely interrupt; must meet or exceed the circuit voltage. |
| Voltage Rating (AC) | 125 V | 125 V | Specifies the maximum AC voltage the fuse can safely interrupt; must meet or exceed the circuit voltage. |
| Interrupting Rating | 50 A @ 125 VAC / 50 A @ 125 VDC | 50 A @ 125 VAC / 50 A @ 125 VDC | Indicates the maximum fault current the fuse can safely break without damage or hazard. |
| Nominal Melting I²t | 2.61 A²s | 7.84 A²s | Represents the energy required to melt the fuse element; affects opening speed under overcurrent and coordination with other protection. |
| DC Cold Resistance | 0.0285 Ohm | 0.0145 Ohm | Lower resistance reduces voltage drop and power loss in normal operation; differs between the two ratings. |
| Fuse Type | Fast-Acting (Nano²) | Fast-Acting (Nano²) | Defines the time-current response; fast-acting is suitable for sensitive electronics requiring quick protection. |
| Package / Size | Nano² SMF, 6.10 x 2.69 mm | Nano² SMF, 6.10 x 2.69 mm | Physical footprint and mounting style must match the PCB layout for drop-in substitutability. |
| Operating Temperature Range | -55°C to +125°C | -55°C to +125°C | Ensures reliable operation across the application's thermal environment. |
| Approvals / Standards | UL, CSA, PSE, cURus | UL, CSA, PSE, cURus | Certification to recognized safety standards is required for compliance in many end products. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 0451003.MRL | 0451005.MRL |
|---|---|---|
| Series | NANO²® 451 | NANO²® 451 |
| Part Status | Active | Active |
| Mounting Type | Surface Mount | Surface Mount |
| Fuse Type | Board Mount (Cartridge Style Excluded) | Board Mount (Cartridge Style Excluded) |
| Current Rating (Amps) | 3 A | 5 A |
| Voltage Rating - AC | 125 V | 125 V |
| Voltage Rating - DC | 125 V | 125 V |
| Response Time | Fast Blow | Fast Blow |
| Breaking Capacity @ Rated Voltage | 50A | 50A |
| Melting I²t | 1.65 | 5.566 |
| Approval Agency | CSA, PSE, UL | CSA, PSE, UL |
| Operating Temperature | -55°C ~ 125°C | -55°C ~ 125°C |
| Size / Dimension | 0.240" L x 0.106" W x 0.106" H (6.10mm x 2.69mm x 2.69mm) | - |
| Packaging | Cut Tape (CT), Tape & Reel (TR) | - |
Frequently asked questions
What are the 0451003.MRL and 0451005.MRL fuses?
The 0451003.MRL and 0451005.MRL are surface-mount fast-acting ceramic body fuses from Littelfuse's 451 series. The 0451003.MRL is rated 3 A and the 0451005.MRL is rated 5 A, both with a voltage rating of 125 VAC/VDC and a breaking capacity of 50 A at 125 VAC/VDC.
What is the main difference between the 0451003.MRL and 0451005.MRL?
The primary difference is the current rating: the 0451003.MRL is rated for 3 A, while the 0451005.MRL is rated for 5 A. Both share the same 451 series platform, package size, voltage rating, and interrupting rating.
Are the 0451003.MRL and 0451005.MRL physically interchangeable?
Yes. Both fuses are offered in the same surface-mount package with identical physical dimensions and terminal configuration, so they are footprint-compatible. However, electrical suitability must be verified for the target circuit.
Can the 0451003.MRL be replaced by the 0451005.MRL in an existing design?
Not automatically. Although the package is the same, the higher 5 A rating of the 0451005.MRL changes the overcurrent protection threshold. The replacement must be evaluated against the circuit's normal operating current, fault current, and the required protection level.
What are the voltage and interrupting ratings of these fuses?
Both the 0451003.MRL and 0451005.MRL are rated 125 VAC/VDC with an interrupting rating of 50 A at 125 VAC/VDC, as specified in the Littelfuse 451 series datasheet.
Do the 0451003.MRL and 0451005.MRL have the same time-current characteristics?
They share the same fast-acting characteristic curve family of the 451 series, but the absolute melting and clearing times differ because of the different current ratings. The 5 A version will carry higher currents before opening compared with the 3 A version.
What are the typical applications for the 0451003.MRL and 0451005.MRL?
These fuses are typically used for overcurrent protection in space-constrained surface-mount circuits such as power supplies, battery packs, consumer electronics, and industrial control boards where a fast-acting ceramic fuse is required.
Are the 0451003.MRL and 0451005.MRL RoHS compliant?
Yes. Both part numbers are listed as RoHS compliant and lead-free in Littelfuse documentation for the 451 series. Designers should confirm the latest compliance status from the manufacturer or authorized distributor before finalizing a bill of materials.