Littelfuse 0438004.WR Surface Mount Fuse 4A 12VAC 32VDC 0603

Part Overview

The Littelfuse 0438004.WR is a 4A surface mount board fuse rated for 12VAC and 32VDC operation in 0603 (1608 Metric) package format. This component is classified as obsolete, making equivalent substitutes necessary for new designs and ongoing production requirements. The fuse provides fast-blow response characteristics with CSA and UL approval certifications, suitable for circuit protection in compact PCB applications.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating - AC	12 V
Voltage Rating - DC	32 V
Response Time	Fast Blow
Package / Case	0603 (1608 Metric)
Mounting Type	Surface Mount
Fuse Type	Board Mount (Cartridge Style Excluded)
Breaking Capacity @ Rated Voltage	50A
Operating Temperature Range	-55°C ~ 150°C
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution eligibility for the 0438004.WR is determined by the following mandatory parameters:

Current Rating: 4 A (exact match required)
Voltage Rating - DC: 32 V (exact match required)
Package / Case: 0603 (1608 Metric) (exact match required)
Mounting Type: Surface Mount (exact match required)
Fuse Type: Board Mount (Cartridge Style Excluded) (exact match required)
Response Time: Fast Blow (exact match required)

All substitute parts listed meet these core electrical and mechanical requirements. Variations in secondary parameters such as melting I²t, DC cold resistance, and operating temperature range do not disqualify substitution when primary parameters align.

Parameter Comparison

Parameter	0438004.WR (Littelfuse)	0438004.WRGT (Littelfuse)	CC06H4A-TR (Eaton)	SF-0603F400-2 (Bourns)
Current Rating (Amps)	4 A	4 A	4 A	4 A
Voltage Rating - AC	12 V	12 V	Not specified	Not specified
Voltage Rating - DC	32 V	32 V	32 V	32 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Package / Case	0603 (1608 Metric)	0603 (1608 Metric)	0603 (1608 Metric)	0603 (1608 Metric)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Fuse Type	Board Mount	Board Mount	Board Mount	Board Mount
Breaking Capacity @ Rated Voltage	50A	50A AC, 50A DC	50A	50A
Melting I²t	0.692	0.739	1	0.239
DC Cold Resistance (Ohms)	0.0169	0.0164	0.018	0.015
Operating Temperature Range	-55°C ~ 150°C	-55°C ~ 150°C	-40°C ~ 85°C	-20°C ~ 105°C
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active
Approval Agency	CSA, UL	CSA, cURus	cULus	UL

Engineering Selection Recommendations

The 0438004.WRGT (Littelfuse) is the primary substitute for the obsolete 0438004.WR. Both parts share identical electrical ratings and operating temperature specifications. The 0438004.WRGT maintains active product status with CSA and cURus certifications, ensuring continued availability and regulatory compliance. The primary distinction is packaging format: the original uses bulk packaging while the substitute is supplied in Tape & Reel format.

The CC06H4A-TR (Eaton) and SF-0603F400-2 (Bourns) are functionally equivalent alternatives that meet all mandatory electrical and mechanical parameters. Both are active products with current regulatory certifications. The CC06H4A-TR operates within a narrower temperature range (-40°C to 85°C) compared to the original specification. The SF-0603F400-2 operates between -20°C and 105°C. Selection between these alternatives depends on application-specific temperature requirements and supply chain considerations.

Frequently Asked Questions (FAQ)

Q: Can the 0438004.WRGT directly replace the 0438004.WR?

A: Yes. Both parts are electrically and mechanically identical with matching 4A current rating, 32VDC voltage rating, 0603 package format, and fast-blow response characteristics. The primary difference is packaging: the substitute is supplied in Tape & Reel format rather than bulk.

Q: Are the Eaton CC06H4A-TR and Bourns SF-0603F400-2 suitable replacements?

A: Yes. Both parts meet the mandatory electrical parameters: 4A current rating, 32VDC voltage rating, 0603 package, surface mount configuration, and fast-blow response. Verify application temperature requirements fall within each substitute's operating range before selection.

Q: What is the significance of the melting I²t variation among substitutes?

A: Melting I²t indicates the thermal energy required to melt the fuse element. Variations (0.239 to 1.0) reflect different fuse element designs among manufacturers. All listed substitutes maintain the same current rating and response time, making them functionally equivalent for circuit protection purposes.

Q: Does the operating temperature range difference affect substitution?

A: The original 0438004.WR operates from -55°C to 150°C. The CC06H4A-TR operates from -40°C to 85°C, and the SF-0603F400-2 from -20°C to 105°C. Substitution is valid only if the application environment remains within the substitute's temperature specification.

Q: Are all substitutes RoHS compliant?

A: Yes. The 0438004.WRGT and SF-0603F400-2 are ROHS3 compliant. The CC06H4A-TR is RoHS compliant. All meet environmental regulatory requirements for new designs.

Q: What certifications should I verify for my application?

A: The original part carries CSA and UL approvals. The 0438004.WRGT maintains CSA and cURus certifications. The CC06H4A-TR carries cULus certification, and the SF-0603F400-2 carries UL certification. Confirm that the selected substitute's certifications align with your application's regulatory requirements.

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