Equivalent & Substitute Parts for 2N4124

Part Overview

The 2N4124 is a through-hole NPN bipolar junction transistor (BJT) rated for 25 V collector-emitter breakdown voltage and 200 mA maximum collector current. Designed for general-purpose switching and amplification applications, this device operates across a temperature range of -55°C to 150°C with a transition frequency of 300 MHz and maximum power dissipation of 625 mW in the TO-92 package.

The 2N4124 is classified as obsolete. Locating equivalent substitute parts becomes necessary when original inventory is depleted or when procurement from legacy suppliers becomes impractical. The 2N4124 PBFREE variant, manufactured by Central Semiconductor Corp, provides a direct functional equivalent with enhanced compliance status and active product availability.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	25	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	625	mW
Frequency - Transition	300	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 2mA, 1V	—
Current - Collector Cutoff (Max)	50	nA
Operating Temperature Range	-55 to 150	°C
Package / Case	TO-92-3 (TO-226)	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitution of the 2N4124 with the 2N4124 PBFREE is based on electrical and mechanical parameter equivalence. Both devices share identical specifications for the following critical parameters:

Transistor type: NPN
Voltage - Collector Emitter Breakdown (Max): 25 V
DC Current Gain (hFE) (Min) @ Ic, Vce: 120 @ 2mA, 1V
Current - Collector Cutoff (Max): 50 nA
Frequency - Transition: 300 MHz
Package / Case: TO-92-3 (TO-226)
Mounting Type: Through Hole
Moisture Sensitivity Level (MSL): 1 (Unlimited)

The 2N4124 PBFREE maintains full electrical compatibility while offering an extended operating temperature range (-65°C to 150°C versus -55°C to 150°C) and improved compliance status. Both devices are classified under ECCN EAR99 and carry REACH Unaffected status.

Parameter Comparison

Parameter	2N4124 (onsemi)	2N4124 PBFREE (Central Semiconductor)
Transistor Type	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	25 V	25 V
Current - Collector Cutoff (Max)	50 nA	50 nA
DC Current Gain (hFE) (Min) @ Ic, Vce	120 @ 2mA, 1V	120 @ 2mA, 1V
Frequency - Transition	300 MHz	300 MHz
Operating Temperature Range	-55°C to 150°C	-65°C to 150°C
Package / Case	TO-92-3 (TO-226)	TO-92-3 (TO-226AA)
Mounting Type	Through Hole	Through Hole
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)
Product Status	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

The 2N4124 PBFREE is a direct electrical substitute for the 2N4124. Selection between these parts should be based on the following factors:

Product Status: The 2N4124 is obsolete, while the 2N4124 PBFREE maintains active product status with 11,548 units in stock. For new designs or long-term production requirements, the 2N4124 PBFREE is the appropriate choice.

Compliance Requirements: The 2N4124 PBFREE carries ROHS3 compliance certification, whereas the original 2N4124 is RoHS non-compliant. Applications subject to RoHS directives or customer specifications requiring RoHS compliance must use the 2N4124 PBFREE.

Operating Temperature Range: The 2N4124 PBFREE extends the lower operating temperature limit to -65°C compared to -55°C for the original part. Applications requiring operation below -55°C benefit from this extended range.

Electrical Equivalence: Both devices are electrically identical across all specified parameters, including voltage ratings, current ratings, gain characteristics, and frequency response. Direct pin-for-pin substitution is supported.

Frequently Asked Questions (FAQ)

Q: Can the 2N4124 PBFREE be used as a direct replacement for the 2N4124?

A: Yes. The 2N4124 PBFREE is electrically and mechanically equivalent to the 2N4124. Both devices share identical collector-emitter breakdown voltage (25 V), collector current rating (200 mA), DC current gain (120 @ 2mA, 1V), transition frequency (300 MHz), and TO-92 package configuration. Pin-for-pin substitution is supported without circuit modification.

Q: What is the difference in operating temperature range between these parts?

A: The 2N4124 operates from -55°C to 150°C, while the 2N4124 PBFREE operates from -65°C to 150°C. The 2N4124 PBFREE provides an additional 10°C of low-temperature capability. For applications operating at or below -55°C, the 2N4124 PBFREE is required.

Q: Are there compliance differences between the 2N4124 and 2N4124 PBFREE?

A: Yes. The 2N4124 PBFREE is ROHS3 compliant, while the original 2N4124 is RoHS non-compliant. Both devices are REACH Unaffected and classified under ECCN EAR99. Applications requiring RoHS compliance must use the 2N4124 PBFREE.

Q: Are the TO-92 packages identical between these parts?

A: Both devices use TO-92-3 through-hole packages suitable for identical PCB footprints. The 2N4124 uses TO-226-3 and TO-92-3 Long Body designation, while the 2N4124 PBFREE uses TO-226-3 and TO-92-3 (TO-226AA) designation. These package variants are mechanically compatible for standard through-hole applications.

Q: What is the moisture sensitivity level for both parts?

A: Both the 2N4124 and 2N4124 PBFREE carry MSL 1 (Unlimited) classification, indicating no moisture sensitivity restrictions. Standard handling and storage procedures apply without special moisture control requirements.

Q: Why is the original 2N4124 listed as obsolete?

A: The 2N4124 is classified as obsolete by the original manufacturer (onsemi). The 2N4124 PBFREE, manufactured by Central Semiconductor Corp, provides continued availability and active product support for this device family.

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