Part A
0451001.MRL
Littelfuse sa.
- Lifecycle
- Active
- Stock
- 7334 PCS
- Package
- 2-SMD
- Series
- Fusibles
Replacement verdict
Compatible functional replacement candidate
The 0451001.MRL and 0451002.MRL are surface-mount fuses from the same Littelfuse NANO2 series, sharing an identical 2410 footprint, voltage rating, and operating temperature range. The primary distinction is the current rating, making the 0451002.MRL a viable higher-current alternative where the circuit design permits. Designers should verify that the increased hold current aligns with their overcurrent protection requirements before substituting.
Current Rating
Not compatible
Voltage Rating
High match
Package Type
High match
Operating Temperature
High match
Parts at a glance
Part B
0451002.MRL
Littelfuse sa.
- Lifecycle
- Active
- Stock
- 4049 PCS
- Package
- 2-SMD
- Series
- Fusibles
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 0451001.MRL | 0451002.MRL | Why it matters |
|---|---|---|---|
| Current Rating | 1 A | 2 A | Determines the maximum continuous current the fuse can carry without opening; a direct functional substitutability constraint. |
| Melting I²t | 0.44 A²s | 1.98 A²s | Indicates the energy required to open the fuse; affects inrush current tolerance and protective coordination. |
| Nominal Cold Resistance | 0.145 Ohm | 0.052 Ohm | Lower resistance reduces voltage drop and power loss in the circuit, impacting efficiency and thermal behavior. |
| Voltage Drop at Rated Current | 0.145 V | 0.104 V | Affects the voltage available to downstream components and overall circuit performance. |
| Voltage Rating | 125 VAC / 125 VDC | 125 VAC / 125 VDC | Defines the maximum circuit voltage the fuse can safely interrupt; must meet or exceed application voltage. |
| Interrupting Rating | 50 A at 125 VAC / 300 A at 125 VDC | 50 A at 125 VAC / 300 A at 125 VDC | Specifies the maximum fault current the fuse can safely break without damage or hazard. |
| Fuse Type | Fast-Acting (Nano²) | Fast-Acting (Nano²) | Determines response speed to overcurrent events; fast-acting is suitable for sensitive electronics protection. |
| Package / Size | Surface Mount, 6.10 x 2.69 mm | Surface Mount, 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 environmental conditions. |
| Agency Approvals | UL, CSA, PSE | UL, CSA, PSE | Certifications confirm compliance with safety standards required for end-product acceptance. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 0451001.MRL | 0451002.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) | 1 A | 2 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 | 0.459 | 0.53 |
| Approval Agency | CSA, PSE, UL | CSA, PSE, UL |
| Operating Temperature | -55°C ~ 125°C | -55°C ~ 125°C |
Frequently asked questions
What are the 0451001.MRL and 0451002.MRL fuses?
The 0451001.MRL and 0451002.MRL are surface-mount fuses from Littelfuse's 451 series, designed for overcurrent protection in compact electronic circuits. The 0451001.MRL is rated 1 A and the 0451002.MRL is rated 2 A, both with a voltage rating of 125 V AC/DC and a breaking capacity of 50 A at 125 V AC/DC.
What is the main difference between the 0451001.MRL and 0451002.MRL?
The primary difference is the current rating: the 0451001.MRL has a rated current of 1 A, while the 0451002.MRL has a rated current of 2 A. Both share the same 125 V AC/DC voltage rating, 50 A breaking capacity, and physical package.
Are the 0451001.MRL and 0451002.MRL physically interchangeable?
Yes, both fuses use the same surface-mount package footprint and have identical physical dimensions, so they are drop-in compatible from a mechanical and PCB land pattern perspective. However, electrical ratings differ, so substitution must be validated against the circuit's current requirements.
What is the voltage rating of the 0451001.MRL and 0451002.MRL?
Both the 0451001.MRL and 0451002.MRL have a voltage rating of 125 V AC/DC, as specified in the Littelfuse 451 series datasheet.
What is the breaking capacity of the 0451001.MRL and 0451002.MRL?
Both fuses have a breaking capacity of 50 A at 125 V AC/DC, meaning they can safely interrupt fault currents up to 50 A at their rated voltage without sustaining damage or causing unsafe conditions.
Can the 0451001.MRL be replaced by the 0451002.MRL in a circuit designed for 1 A?
No, replacing a 1 A fuse with a 2 A fuse is not a direct substitution. The higher current rating may fail to protect the circuit under overcurrent conditions, potentially allowing excessive current to damage downstream components. Always match the fuse rating to the circuit design requirements.
What are the typical applications for the 0451001.MRL and 0451002.MRL?
These fuses are typically used in space-constrained consumer electronics, battery packs, power supplies, and portable devices where surface-mount overcurrent protection is required. The 1 A version suits lower-current circuits, while the 2 A version is used in circuits drawing higher operating currents.
Do the 0451001.MRL and 0451002.MRL have the same time-current characteristics?
Both fuses belong to the same Littelfuse 451 series and share the same time-current curve family, but the absolute melting times differ because of the different current ratings. The 0451002.MRL will carry higher currents before opening compared to the 0451001.MRL under the same fault conditions.