Part A
0451005.MRL
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 6135 PCS
- Package
- 2-SMD
- Series
- Fuses
Replacement verdict
Compatible functional replacement candidate
The 0451002.MRL and 0451005.MRL are both surface-mount fast-acting ceramic fuses from the Littelfuse 451 series, sharing identical package, voltage, and interrupting ratings. The primary distinction is the current rating, making the 0451005.MRL a viable higher-current alternative only where the circuit design and upstream protection can accommodate the increased amperage.
Current Rating
Not compatible
Voltage Rating
High match
Package Type
High match
Interrupting Rating
High match
Parts at a glance
Part B
0451002.MRL
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 4049 PCS
- Package
- 2-SMD
- Series
- Fuses
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | 0451002.MRL | 0451005.MRL | Why it matters |
|---|---|---|---|
| Current Rating | 2 A | 5 A | Determines the maximum continuous current the fuse can carry without opening; a direct functional substitutability constraint. |
| 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 at 125 VAC / 50 A at 125 VDC | 50 A at 125 VAC / 50 A at 125 VDC | Indicates the maximum fault current the fuse can safely break without damage or hazard. |
| Nominal Melting I²t | 1.6 A²s | 12.8 A²s | Represents the energy required to melt the fuse element; affects opening speed and coordination with downstream components. |
| Nominal Voltage Drop | 0.14 V | 0.11 V | Lower voltage drop reduces power loss and heat generation in the circuit during normal operation. |
| Nominal Cold Resistance | 0.0700 Ohms | 0.0220 Ohms | Affects inrush current behavior and steady-state power dissipation; lower resistance is generally preferred for higher currents. |
| Fuse Type | Fast-Acting | Fast-Acting | Defines the time-current response; fast-acting fuses protect sensitive components from rapid overcurrent events. |
| Package / Size | Nano2 (SMF) 6.1 x 2.69 mm | Nano2 (SMF) 6.1 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 and proper derating across the application's environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 0451005.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) | 5 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 | 5.566 | 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 0451002.MRL and 0451005.MRL fuses?
The 0451002.MRL and 0451005.MRL are Littelfuse Nano2 SMF surface-mount fuses in the 451 series. The 0451002.MRL is rated 2 A and the 0451005.MRL is rated 5 A, both with a 125 V AC voltage rating and a 50 A interrupting rating at 125 V AC.
What is the main difference between the 0451002.MRL and 0451005.MRL?
The primary difference is the current rating: the 0451002.MRL is a 2 A fuse, while the 0451005.MRL is a 5 A fuse. They share the same 451 series Nano2 SMF package, 125 V AC voltage rating, and 50 A interrupting rating at 125 V AC.
Are the 0451002.MRL and 0451005.MRL interchangeable?
No. Although they share the same package and voltage rating, their current ratings differ (2 A vs. 5 A). Substitution must be evaluated against the circuit's normal operating current, inrush profile, and required overcurrent protection level using the manufacturer datasheet.
What is the voltage rating of the 0451002.MRL and 0451005.MRL?
Both the 0451002.MRL and 0451005.MRL are rated for 125 V AC.
What is the interrupting rating of the 0451002.MRL and 0451005.MRL?
Both fuses have an interrupting rating of 50 A at 125 V AC.
What package do the 0451002.MRL and 0451005.MRL use?
Both the 0451002.MRL and 0451005.MRL use the Littelfuse Nano2 SMF surface-mount package, which is part of the 451 series.
Do the 0451002.MRL and 0451005.MRL have the same physical dimensions?
Yes. Because both are 451 series Nano2 SMF fuses, they share the same surface-mount package footprint and physical dimensions as specified in the Littelfuse 451 series datasheet.
Which applications are suitable for the 0451002.MRL versus the 0451005.MRL?
Selection depends on the circuit's steady-state current and required protection threshold. The 0451002.MRL is intended for circuits with lower normal operating current, while the 0451005.MRL is intended for circuits with higher normal operating current, provided the circuit voltage does not exceed 125 V AC and fault current does not exceed the 50 A interrupting rating.