Littelfuse NANO²® 452 0452012.MRSN Surface Mount Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0452012.MRSN is a 12 A, 72 V AC surface mount board mount fuse in the NANO²® 452 series. This slow blow fuse is designed for circuit protection in applications requiring reliable overcurrent protection with a 2-SMD, square end block package configuration. The part is actively manufactured and maintains full compliance with RoHS3 and REACH regulations. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to packaging availability, inventory constraints, or specific application requirements.

Substiute Parts

0452012.MRSN

Littelfuse Inc.In Stock: 8000452012.MRSN Datasheet

Current PartRFQ

0452012.MRL

Littelfuse Inc.In Stock: 151250452012.MRL Datasheet

Parametric EquivalentRFQ

0454012.MR

Littelfuse Inc.In Stock: 40040454012.MR Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 0452012.MRSN are qualified based on the following critical parameters that determine functional and mechanical interchangeability:

• Current Rating: 12 A (exact match required)
• Voltage Rating (AC): 72 V (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Surface Mount (exact match required)
• Package / Case: 2-SMD, Square End Block (exact match required)
• Breaking Capacity @ Rated Voltage: 50 A (exact match required)
• Melting I²t: 260.46 (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)
• DC Cold Resistance: 0.0061 Ohms (exact match required)
• Physical Dimensions: 0.240" L x 0.106" W x 0.106" H (exact match required)

Substitute parts may differ in packaging format (Tape & Reel versus Cut Tape & Digi-Reel®) and series designation within the NANO²® family, provided all electrical and mechanical parameters remain identical.

Parameter Comparison

Engineering Selection Recommendations

All three parts—0452012.MRSN, 0452012.MRL, and 0454012.MR—are active products manufactured by Littelfuse Inc. and maintain full compliance with RoHS3 and REACH regulations. Selection between these parts is determined by packaging and distribution format requirements rather than electrical or mechanical performance differences.

The 0452012.MRSN and 0452012.MRL are both supplied in Tape & Reel (TR) format and carry CSA and UR approvals. The 0454012.MR is supplied in Cut Tape (CT) & Digi-Reel® format and carries CSA and UL approvals. All three parts share identical electrical characteristics, thermal performance, and physical dimensions, making them functionally interchangeable in circuit protection applications requiring 12 A, 72 V AC slow blow fuse protection.

Frequently Asked Questions (FAQ)

Q: Can 0452012.MRL be used as a direct replacement for 0452012.MRSN?

A: Yes. Both parts are identical in electrical performance, thermal characteristics, and physical dimensions. The primary difference is packaging format (both are Tape & Reel) and DC voltage rating specification. The 0452012.MRL explicitly specifies 60 V DC rating, while the 0452012.MRSN does not specify a DC rating. For AC-only applications, both are equivalent.

Q: What is the difference between 0452012.MRL and 0454012.MR?

A: The electrical and mechanical specifications are identical. The differences are: series designation (NANO²® 452 versus NANO²® 454), packaging format (Tape & Reel versus Cut Tape & Digi-Reel®), and approval agency (CSA/UR versus CSA/UL). Selection depends on packaging requirements and regional certification needs.

Q: Are these parts suitable for both AC and DC applications?

A: The 0452012.MRSN is rated for 72 V AC. The 0452012.MRL and 0454012.MR are rated for 72 V AC and 60 V DC. For DC applications, use 0452012.MRL or 0454012.MR.

Q: What does the 2-SMD, Square End Block package mean?

A: This refers to a surface mount fuse package with two solder pads (SMD = Surface Mount Device) in a square end block configuration. All three parts use this identical package, ensuring mechanical compatibility on PCBs designed for this form factor.

Q: Are all three parts RoHS3 compliant?

A: Yes. All three parts—0452012.MRSN, 0452012.MRL, and 0454012.MR—are ROHS3 compliant and REACH unaffected, meeting environmental and regulatory requirements for industrial and consumer applications.