Littelfuse 0473003.MRT1HF PICO® II 473 Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0473003.MRT1HF is a 3 A, 125 V AC/DC board mount axial fuse from the PICO® II 473 series, designed for through-hole mounting applications. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance requirements. Active alternatives within the same series provide identical electrical and mechanical specifications with improved availability.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Through Hole
Package / Case	Axial
Breaking Capacity @ Rated Voltage	50 A
Melting I²t	21
Operating Temperature Range	-55°C to 125°C
Size / Dimension	0.135" Dia x 0.280" L (3.43 mm x 7.11 mm)
DC Cold Resistance	0.038 Ohms
RoHS Status	ROHS3 Compliant
Approval Agencies	CSA, PSE, UR

Substitute Part Grouping Explanation

Substitution of the 0473003.MRT1HF is determined by strict equivalence across the following critical parameters:

Current Rating: 3 A (exact match required)
Voltage Rating: 125 V AC and 125 V DC (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Through Hole (exact match required)
Package / Case: Axial (exact match required)
Breaking Capacity: 50 A (exact match required)
Melting I²t: 21 (exact match required)
Operating Temperature Range: -55°C to 125°C (exact match required)
Physical Dimensions: 0.135" Dia x 0.280" L (exact match required)
DC Cold Resistance: 0.038 Ohms (exact match required)
Regulatory Compliance: CSA, PSE, UR certifications (exact match required)

All substitute parts listed below meet these criteria and belong to the same PICO® II 473 series. The primary distinction among substitutes is product status (active vs. obsolete) and packaging configuration (Cut Tape vs. other formats).

Parameter Comparison

Part Number	Manufacturer	Product Status	Packaging	Current Rating (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Breaking Capacity (A)	Melting I²t	Operating Temp (°C)	Inventory (Pcs)
0473003.MRT1HF	Littelfuse Inc.	Obsolete	-	3	125	125	Slow Blow	50	21	-55 to 125	709
0473003.MRT1L	Littelfuse Inc.	Active	Cut Tape (CT)	3	125	125	Slow Blow	50	21	-55 to 125	2400
0473003.HAT1L	Littelfuse Inc.	Active	Cut Tape (CT)	3	125	125	Slow Blow	50	21	-55 to 125	1030
0473003.MAT1L	Littelfuse Inc.	Active	Cut Tape (CT)	3	125	125	Slow Blow	50	21	-55 to 125	1851
0473003.YRT1L	Littelfuse	Active	Cut Tape (CT)	3	125	125	Slow Blow	50	21	-55 to 125	20100

Engineering Selection Recommendations

All substitute parts listed are active products with full regulatory compliance (CSA, PSE, UR certifications) and ROHS3 compliance. The 0473003.MRT1HF is obsolete; therefore, selection of an active substitute is necessary for new designs and ongoing production.

For immediate availability and supply chain continuity, 0473003.YRT1L offers the highest inventory level (20,100 pcs) while maintaining identical electrical and mechanical specifications. 0473003.MRT1L provides the second-highest availability (2,400 pcs) and represents a direct packaging equivalent. 0473003.HAT1L and 0473003.MAT1L are also active alternatives with lower but adequate inventory levels.

All substitutes are packaged in Cut Tape (CT) format, which is standard for production environments. Packaging differences do not affect electrical performance or mechanical compatibility in through-hole mounting applications.

Frequently Asked Questions (FAQ)

Q: Can 0473003.MRT1L be used as a direct replacement for 0473003.MRT1HF?

A: Yes. Both parts share identical electrical ratings (3 A, 125 V AC/DC), response characteristics (Slow Blow), mechanical dimensions (0.135" Dia x 0.280" L), and regulatory certifications. The primary difference is product status: 0473003.MRT1HF is obsolete, while 0473003.MRT1L is active. Packaging differs (unspecified vs. Cut Tape), but this does not affect circuit performance.

Q: Are all substitute parts interchangeable in the same PCB footprint?

A: Yes. All substitute parts maintain identical physical dimensions (0.135" Dia x 0.280" L), axial package configuration, and through-hole mounting requirements. No PCB redesign is necessary.

Q: What is the difference between the various substitute part numbers?

A: All substitute parts (0473003.MRT1L, 0473003.HAT1L, 0473003.MAT1L, 0473003.YRT1L) are parametrically equivalent and belong to the PICO® II 473 series. Differences in part number suffixes reflect internal Littelfuse manufacturing or distribution codes and do not indicate functional or electrical differences. All meet identical specifications for current rating, voltage rating, response time, breaking capacity, and operating temperature range.

Q: Which substitute should be selected for new production?

A: Selection should prioritize active products with adequate inventory. 0473003.YRT1L offers the highest stock level (20,100 pcs), followed by 0473003.MRT1L (2,400 pcs). Both are suitable for new production designs. Verify packaging requirements (Cut Tape format) align with assembly processes.

Q: Are there any compliance or certification differences among the substitutes?

A: No. All substitute parts carry identical regulatory approvals (CSA, PSE, UR) and ROHS3 compliance status. No additional qualification or testing is required when switching between listed substitutes.

Q: What is the melting I²t value, and why is it important for substitution?

A: The melting I²t value of 21 defines the thermal energy required to melt the fuse element. This parameter must match exactly across all substitutes to ensure identical overcurrent protection characteristics and response behavior in the circuit. All listed substitutes maintain this specification.

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