2N4124G Equivalent & Substitute Parts

Part Overview

The 2N4124G is an NPN bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 200 mA, collector-emitter breakdown voltage of 25 V, and a transition frequency of 300 MHz in a through-hole TO-92 package. The 2N4124G is classified as obsolete, making identification of functionally equivalent substitute parts essential for ongoing design support and production continuity.

Substiute Parts

2N4124G

onsemiIn Stock: 16242N4124G Datasheet

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MMBT4124LT1G

onsemiIn Stock: 24424MMBT4124LT1G Datasheet

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2N4124 PBFREE

Central Semiconductor CorpIn Stock: 116412N4124 PBFREE Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 2N4124G are identified based on electrical parameter equivalence and functional compatibility. The primary substitution criteria are:

Electrical Parameters (Must Match or Exceed):

• Transistor Type: NPN
• Maximum Collector Current (Ic): 200 mA minimum
• Collector-Emitter Breakdown Voltage (Vce): 25 V minimum
• DC Current Gain (hFE): 120 minimum at specified conditions
• Transition Frequency: 300 MHz minimum
• Vce Saturation: 300 mV maximum at specified bias conditions
• Collector Cutoff Current (ICBO): 50 nA maximum

Mechanical Compatibility:

• Package type determines mounting compatibility (through-hole versus surface-mount)
• Pin configuration must maintain functional equivalence

Two substitute parts meet these criteria with different packaging approaches: the MMBT4124LT1G provides surface-mount functionality in SOT-23-3 package, while the 2N4124 PBFREE maintains through-hole compatibility in TO-92-3 package.

Parameter Comparison

Engineering Selection Recommendations

For Through-Hole Applications:

The 2N4124 PBFREE manufactured by Central Semiconductor Corp is the direct through-hole substitute for the obsolete 2N4124G. This part maintains identical TO-92-3 package compatibility, matching pin configuration and board layout requirements. The 2N4124 PBFREE is ROHS3 compliant and active in production, ensuring long-term availability. Operating temperature range extends to -65°C, providing enhanced low-temperature performance compared to the original 2N4124G specification of -55°C.

For Surface-Mount Applications:

The MMBT4124LT1G manufactured by onsemi provides electrical equivalence in a surface-mount SOT-23-3 package. This part is manufactured by the original equipment supplier and is ROHS3 compliant. The maximum power dissipation is 225 mW, which is lower than the through-hole variant (625 mW) due to package thermal characteristics. This part is suitable for applications where power dissipation remains within the 225 mW limit.

Compliance Considerations:

Both substitute parts carry REACH Unaffected status and EAR99 ECCN classification, matching the regulatory profile of the original 2N4124G. Both substitutes are ROHS3 compliant, supporting modern manufacturing and environmental compliance requirements.

Frequently Asked Questions (FAQ)

Q: Can the MMBT4124LT1G replace the 2N4124G in existing through-hole designs?

A: No. The MMBT4124LT1G uses a surface-mount SOT-23-3 package, while the 2N4124G uses a through-hole TO-92-3 package. These packages have different physical dimensions, pin spacing, and mounting methods. Board layout and assembly process modifications are required for surface-mount substitution. For through-hole designs, use the 2N4124 PBFREE.

Q: What is the key difference between the 2N4124G and 2N4124 PBFREE?

A: Both parts share identical electrical specifications and through-hole TO-92-3 packaging. The primary differences are manufacturer (onsemi versus Central Semiconductor Corp), product status (obsolete versus active), and RoHS compliance (not specified versus ROHS3 compliant). The 2N4124 PBFREE offers extended low-temperature operation to -65°C compared to -55°C for the 2N4124G.

Q: Why is the maximum power rating different between the MMBT4124LT1G (225 mW) and the 2N4124G (625 mW)?

A: Power dissipation capability is determined by package thermal characteristics. The through-hole TO-92-3 package provides superior heat dissipation to the environment compared to the surface-mount SOT-23-3 package. The lower power rating of the MMBT4124LT1G reflects this thermal limitation, not a difference in transistor die performance.

Q: Are all three parts pin-compatible?

A: The 2N4124G and 2N4124 PBFREE are pin-compatible, both using three-pin TO-92-3 configuration. The MMBT4124LT1G also uses three pins in SOT-23-3 configuration with equivalent functional pin assignment (Base, Collector, Emitter), but physical pin spacing and package dimensions differ significantly.

Q: Can I use the MMBT4124LT1G in a circuit designed for the 2N4124G if I modify the PCB layout?

A: Electrical substitution is valid if circuit power dissipation remains below 225 mW. However, PCB layout modifications, different soldering processes (reflow versus wave solder), and assembly procedure changes are required. Design verification is necessary to confirm thermal and electrical performance in the specific application context.

Q: What compliance certifications apply to all substitute parts?

A: All three parts (2N4124G, MMBT4124LT1G, and 2N4124 PBFREE) carry REACH Unaffected status and EAR99 ECCN classification. The MMBT4124LT1G and 2N4124 PBFREE are ROHS3 compliant. Moisture sensitivity level is 1 (Unlimited) for all parts.