MMST4124-7-F Equivalent & Substitute Parts

Part Overview

The MMST4124-7-F is an NPN bipolar junction transistor manufactured by Diodes Incorporated in a surface mount SOT-323 package. This device is rated for 25 V collector-emitter breakdown voltage and 200 mA maximum collector current, with a maximum power dissipation of 200 mW and transition frequency of 300 MHz. The part is classified as obsolete, necessitating identification of functionally equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain electrical and mechanical compatibility within the specified parameter ranges.

Substiute Parts

MMST4124-7-F

Diodes IncorporatedIn Stock: 3248MMST4124-7-F Datasheet

Current PartRFQ

MMST3904-7-F

Diodes IncorporatedIn Stock: 65337MMST3904-7-F Datasheet

MFR RecommendedRFQ

BC848BWT1G

onsemiIn Stock: 24056BC848BWT1G Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MMST4124-7-F is determined by the following critical electrical and mechanical parameters:

Mandatory Compatibility Criteria:

• Transistor type: NPN polarity
• Package: SOT-323 (SC-70) surface mount configuration
• Collector current rating: minimum 200 mA
• Operating temperature range: -55°C to 150°C
• Mounting type: Surface mount

Electrical Performance Criteria:

• Collector-emitter breakdown voltage: must equal or exceed 25 V
• Power dissipation: must equal or exceed 200 mW
• Transition frequency: must equal or exceed 300 MHz
• Saturation voltage and DC current gain characteristics must support equivalent circuit operation

Substitute parts are grouped based on whether they meet or exceed these parameters while maintaining the same physical package and mounting interface.

Parameter Comparison

Engineering Selection Recommendations

MMST3904-7-F (Diodes Incorporated)

The MMST3904-7-F is the primary manufacturer-recommended substitute for the MMST4124-7-F. Both devices are manufactured by Diodes Incorporated and share identical packaging (SOT-323), mounting type (surface mount), and power rating (200 mW). The MMST3904-7-F provides enhanced voltage rating (40 V versus 25 V) and maintains the same collector current capacity (200 mA), transition frequency (300 MHz), and saturation voltage characteristics (300 mV @ 5 mA, 50 mA). Both parts are ROHS3 compliant with MSL 1 rating. The MMST3904-7-F is currently in active production status, ensuring long-term availability and supply chain continuity.

BC848BWT1G (onsemi)

The BC848BWT1G is an alternative substitute manufactured by onsemi in the same SOT-323 package. This device maintains the same operating temperature range (-55°C to 150°C) and compliance certifications (ROHS3, MSL 1). However, the BC848BWT1G has reduced electrical performance specifications: maximum collector current of 100 mA (versus 200 mA), maximum power dissipation of 150 mW (versus 200 mW), and transition frequency of 100 MHz (versus 300 MHz). The saturation voltage is higher at 600 mV @ 5 mA, 100 mA. The BC848BWT1G is suitable only for applications where the reduced current and frequency specifications are acceptable. This part is currently in active production status.

Frequently Asked Questions (FAQ)

Q: Can the MMST3904-7-F directly replace the MMST4124-7-F in all applications?

A: The MMST3904-7-F is electrically compatible as a direct substitute. Both devices share identical collector current (200 mA), power rating (200 mW), transition frequency (300 MHz), and saturation voltage characteristics. The MMST3904-7-F provides higher voltage rating (40 V versus 25 V), which is advantageous for circuits operating at or near the original 25 V specification. Both parts use the same SOT-323 package with identical pinout and mounting requirements.

Q: What are the limitations of using BC848BWT1G as a substitute?

A: The BC848BWT1G has three significant electrical limitations compared to the MMST4124-7-F. First, maximum collector current is 100 mA, limiting applications requiring the full 200 mA capacity. Second, transition frequency is 100 MHz, insufficient for circuits requiring 300 MHz performance. Third, power dissipation is limited to 150 mW versus 200 mW. The BC848BWT1G is suitable only for low-current, low-frequency applications within these reduced specifications.

Q: Are all substitute parts available in the same packaging?

A: Yes. The MMST4124-7-F, MMST3904-7-F, and BC848BWT1G are all manufactured in the SOT-323 (SC-70) surface mount package. All three devices have identical physical dimensions and pinout configuration, enabling direct PCB layout compatibility without redesign.

Q: What compliance certifications apply to substitute parts?

A: Both substitute parts (MMST3904-7-F and BC848BWT1G) are ROHS3 compliant and carry MSL 1 (Unlimited) moisture sensitivity rating, matching the original MMST4124-7-F. Both are REACH unaffected and classified as EAR99 for export control purposes.

Q: Which substitute should be selected for new designs?

A: The MMST3904-7-F is the recommended choice for new designs. It is manufactured by the same supplier as the original part, maintains all electrical performance specifications, and is in active production status. The MMST3904-7-F provides enhanced voltage margin (40 V rating) for improved circuit reliability. The BC848BWT1G should be selected only when application requirements are limited to 100 mA collector current and 100 MHz frequency operation.

Q: What is the impact of different DC current gain (hFE) specifications?

A: The MMST4124-7-F specifies minimum hFE of 120 @ 2 mA, 1 V. The MMST3904-7-F specifies minimum hFE of 100 @ 10 mA, 1 V, measured at different bias conditions. The BC848BWT1G specifies minimum hFE of 200 @ 2 mA, 5 V. These differences reflect measurement conditions rather than fundamental device capability. Circuit designs using base current limiting or feedback biasing are unaffected by these variations. Designs relying on specific hFE values require verification against the actual measurement conditions specified for each part.