Littelfuse 02301.25DRT1SW Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 02301.25DRT1SW is a 1.25 A, 250 V AC glass cartridge fuse with slow-blow response characteristics, designed for through-hole mounting in axial configuration. This part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for continued circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	1.25 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	Cartridge, Non-Standard (Axial)
Mounting Type	Through Hole
Size / Dimension	0.177" Dia x 0.571" L (4.50mm x 14.50mm)
Melting I²t	9.8
Operating Temperature Range	-55°C ~ 125°C
DC Cold Resistance	0.145 Ohms

Substitute Part Grouping Explanation

Substitution of the 02301.25DRT1SW is determined by strict equivalence across the following critical parameters:

Current Rating: 1.25 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Physical Dimensions: 0.177" Dia x 14.50mm L (exact match required)
Melting I²t: 9.8 (exact match required)
Mounting Type: Through Hole, Axial (exact match required)

All substitute parts listed maintain these electrical and mechanical parameters. Active substitute parts additionally provide DC voltage rating (125 V DC) and enhanced regulatory compliance compared to the obsolete main part.

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage AC (V)	Voltage DC (V)	Response Time	Melting I²t	DC Resistance (Ω)	Product Status	RoHS Status	Packaging
02301.25DRT1SW	Littelfuse Inc.	1.25	250	—	Slow Blow	9.8	0.145	Obsolete	RoHS Non-Compliant	Bulk
02301.25DRT1SP	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25DRT1P	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25DRT2P	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25DRT2SP	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25DRT3P	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25DRT3SP	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25MRT1EP	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel
02301.25MRT1SSP	Littelfuse Inc.	1.25	250	125	Slow Blow	9.8	0.146	Active	ROHS3 Compliant	Tape & Reel

Engineering Selection Recommendations

All listed substitute parts are active products manufactured by Littelfuse Inc. and maintain full electrical and mechanical equivalence to the 02301.25DRT1SW. The substitute parts provide enhanced regulatory compliance through ROHS3 certification and expanded DC voltage rating (125 V DC), extending application flexibility while preserving AC circuit protection characteristics.

Substitute parts are supplied in Tape & Reel packaging, suitable for automated assembly processes. The main part's bulk packaging format is replaced by standard industry tape and reel configuration across all active alternatives.

All substitute parts carry identical approval agency certifications (CE, CSA, PSE, UL) and maintain the same operating temperature range (-55°C ~ 125°C) and physical dimensions as the obsolete main part.

Frequently Asked Questions (FAQ)

Q: Can any of these substitute parts directly replace the 02301.25DRT1SW in existing designs?

A: Yes. All listed substitute parts maintain identical current rating (1.25 A), AC voltage rating (250 V), fuse type (glass cartridge), response time (slow blow), physical dimensions (0.177" Dia x 0.571" L), and melting I²t (9.8). Through-hole axial mounting compatibility is preserved across all alternatives.

Q: What is the difference between the DRT and MRT series within the substitute list?

A: Both series maintain the specified electrical and mechanical parameters. The distinction lies in internal design characteristics not provided in the parameter set. Selection between series should be based on application-specific requirements and design validation.

Q: Does the addition of 125 V DC rating on substitute parts affect AC circuit operation?

A: No. The 125 V DC rating represents an expanded capability specification. AC circuit protection at 250 V remains unchanged. The DC rating provides additional application flexibility without altering AC performance characteristics.

Q: Are there packaging considerations when transitioning from the obsolete part?

A: Yes. The 02301.25DRT1SW is supplied in bulk packaging, while all active substitutes are supplied in Tape & Reel format. This change requires adjustment to receiving, storage, and assembly processes but does not affect electrical or mechanical compatibility.

Q: What regulatory compliance improvements are provided by the substitute parts?

A: Substitute parts are ROHS3 compliant, whereas the main part is RoHS non-compliant. This addresses environmental and regulatory requirements for new designs and manufacturing processes. All substitute parts maintain the same approval agency certifications (CE, CSA, PSE, UL) as the main part.

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