SMM 20 Equivalent & Substitute Parts Reference

Part Overview

The SMM 20 is a 20 A surface mount board mount fuse rated for 250 V AC and 72 V DC operation, manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The SMM 20 features a 2-SMD square end block package with medium blow response characteristics and is approved for CE and cURus compliance.

Substiute Parts

SMM 20

Bel Fuse Inc.In Stock: 724SMM 20 Datasheet

Current PartRFQ

0678L9150-02

Bel Fuse Inc.In Stock: 420600678L9150-02 Datasheet

DirectRFQ

0678L9200-02

Bel Fuse Inc.In Stock: 668790678L9200-02 Datasheet

DirectRFQ

0456020.ER

Littelfuse Inc.In Stock: 320680456020.ER Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SMM 20 are categorized based on the following critical parameters that determine functional equivalence:

Direct Equivalents maintain identical electrical specifications:

• Current Rating: 20 A
• Voltage Rating - AC: 250 V
• Voltage Rating - DC: 72 V
• Package / Case: 2-SMD, Square End Block
• Mounting Type: Surface Mount
• Operating Temperature Range: -55°C ~ 125°C

Similar Substitutes share the same current rating and package form factor but operate at different voltage ratings and response characteristics. These require circuit-level evaluation to confirm compatibility with the application's voltage requirements.

Parameter Comparison

Engineering Selection Recommendations

0678L9200-02 is the primary direct equivalent for SMM 20 replacement. This part maintains identical electrical ratings (20 A, 250 V AC, 72 V DC) and mechanical specifications. The 0678L9200-02 is active in production with AEC-Q200 automotive qualification and cURus approval, providing enhanced compliance coverage compared to the obsolete SMM 20. RoHS3 compliance is confirmed.

0678L9150-02 is a current-reduced variant rated at 15 A with identical voltage specifications and package form factor. This substitute is applicable only in circuits where the 15 A rating satisfies the design requirement. The part is active with AEC-Q200 and cURus certifications.

0456020.ER (Littelfuse NANO²® 456 series) shares the 20 A current rating and surface mount package but operates at reduced voltage ratings (125 V AC, 100 V DC) and exhibits fast blow response characteristics. This part is suitable only for applications operating within these voltage limits and requiring fast response protection. The higher DC breaking capacity (300 A) and lower melting I²t (18) indicate different protection characteristics.

Frequently Asked Questions (FAQ)

Q: Can 0678L9200-02 directly replace SMM 20 in all applications?

A: Yes. The 0678L9200-02 maintains identical current rating (20 A), AC voltage rating (250 V), DC voltage rating (72 V), package form factor (2-SMD square end block), and operating temperature range (-55°C ~ 125°C). Both parts feature medium blow response. The primary difference is product status: SMM 20 is obsolete while 0678L9200-02 is active production with AEC-Q200 qualification.

Q: When is 0678L9150-02 appropriate as a substitute?

A: The 0678L9150-02 is appropriate only when the circuit design permits a 15 A current rating. Voltage ratings (250 V AC, 72 V DC), package form factor, and operating temperature range are identical to SMM 20. This part should not be used in applications requiring 20 A protection.

Q: What are the limitations of 0456020.ER as a substitute?

A: The 0456020.ER operates at reduced voltage ratings (125 V AC versus 250 V AC; 100 V DC versus 72 V DC) and exhibits fast blow response instead of medium blow. This part is suitable only for circuits operating within these lower voltage limits and where fast response protection is acceptable. The different response time and melting I²t characteristics (18 versus 270) indicate different protection profiles.

Q: Are there package compatibility concerns with these substitutes?

A: All substitute parts use the 2-SMD square end block package identical to SMM 20. Surface mount assembly compatibility is maintained across all options.

Q: What compliance certifications should be considered?

A: SMM 20 carries CE and cURus approval. The 0678L9200-02 and 0678L9150-02 provide AEC-Q200 automotive qualification in addition to cURus approval. The 0456020.ER carries cULus and PSE certifications. Application requirements determine which certification set is necessary.