Part A
0451003.MRL
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 7735 Stückzahl
- Series
- Sicherungen
Replacement verdict
Compatible functional replacement candidate
The 0451001.MRL and 0451003.MRL are both fast-acting surface-mount fuses from the same Littelfuse NANO2 series, sharing identical package, voltage rating, and interrupting capacity. The only meaningful difference is the current rating, making the 0451003.MRL a viable higher-current alternative for the 0451001.MRL provided the application's overcurrent protection threshold is adjusted accordingly.
Current Rating
Validation required
Package Type
High match
Voltage Rating
High match
Breaking Capacity
High match
Parts at a glance
Part B
0451001.MRL
Littelfuse Inc.
- Lifecycle
- Active
- Stock
- 7334 Stückzahl
- Package
- 2-SMD
- Series
- Sicherungen
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 | 0451003.MRL | Why it matters |
|---|---|---|---|
| Current Rating | 1 A | 3 A | Determines the maximum continuous current the fuse can carry without opening; a direct functional difference affecting circuit protection level. |
| Voltage Rating (AC) | 125 V | 125 V | Specifies the maximum AC voltage the fuse can safely interrupt; must meet or exceed the circuit voltage. |
| Voltage Rating (DC) | 125 V | 125 V | Specifies the maximum DC voltage the fuse can safely interrupt; critical for DC applications. |
| 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. |
| Melting I²t | 0.42 A²s | 3.6 A²s | Represents the thermal energy required to open the fuse; affects response time and coordination with other protection devices. |
| Nominal Cold Resistance | 0.145 Ohms | 0.028 Ohms | Lower resistance reduces voltage drop and power loss in the circuit; differs significantly between the two ratings. |
| Voltage Drop at Rated Current | 0.145 V | 0.084 V | Affects circuit efficiency and heat generation; lower drop is preferable for power-sensitive designs. |
| Fuse Type | Fast-Acting (Nano²) | Fast-Acting (Nano²) | Defines the time-current characteristic; fast-acting is suitable for sensitive electronics protection. |
| Package / Size | Nano² SMF (6.1 mm x 2.69 mm) | Nano² SMF (6.1 mm x 2.69 mm) | Physical footprint and mounting type must match the PCB layout for direct substitutability. |
| Operating Temperature Range | -55°C to +125°C | -55°C to +125°C | Ensures reliable operation across the application's environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | 0451003.MRL | 0451001.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 | 1 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 | 0.459 |
| 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 0451001.MRL and 0451003.MRL fuses?
The 0451001.MRL and 0451003.MRL are surface-mount fast-acting ceramic body fuses from Littelfuse's 451 series. The 0451001.MRL is rated 1 A and the 0451003.MRL is rated 3 A, both with a 125 V AC voltage rating and a 2410 (6125 metric) package footprint.
What is the main difference between the 0451001.MRL and 0451003.MRL?
The primary difference is the current rating: the 0451001.MRL is rated 1 A while the 0451003.MRL is rated 3 A. Both share the same 125 V AC voltage rating, fast-acting characteristic, ceramic body construction, and 2410 surface-mount package.
Are the 0451001.MRL and 0451003.MRL interchangeable in a circuit?
No. Although they share the same package and voltage rating, their current ratings differ (1 A vs 3 A). Substituting one for the other changes the overcurrent protection threshold and is not acceptable unless the circuit design has been validated for the alternate rating.
What is the voltage rating of the 0451001.MRL and 0451003.MRL?
Both the 0451001.MRL and 0451003.MRL have a voltage rating of 125 V AC. They should not be used in circuits exceeding this voltage rating.
What package size do the 0451001.MRL and 0451003.MRL use?
Both fuses use the 2410 (6125 metric) surface-mount package, which has a body size of approximately 6.1 mm x 2.5 mm. This allows them to share the same PCB land pattern.
Are the 0451001.MRL and 0451003.MRL fast-acting or time-delay fuses?
Both the 0451001.MRL and 0451003.MRL are fast-acting fuses. They are designed to open quickly under overcurrent conditions, making them suitable for protecting sensitive electronic circuits.
What breaking capacity do the 0451001.MRL and 0451003.MRL have?
Both the 0451001.MRL and 0451003.MRL have a breaking capacity of 50 A at 125 V AC. This is the maximum fault current the fuse can safely interrupt without damage or hazardous failure.
What are the typical applications for the 0451001.MRL and 0451003.MRL?
These fuses are typically used for overcurrent protection in consumer electronics, power supplies, battery chargers, and other compact electronic devices where a surface-mount fast-acting fuse with a 125 V AC rating is required. The 1 A version suits lower-current rails, while the 3 A version suits higher-current rails.