2N4123-AP Equivalent & Substitute Parts

Part Overview

The 2N4123-AP is an NPN bipolar junction transistor manufactured by Micro Commercial Co, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 200 mA, collector-emitter breakdown voltage of 30 V, and a power dissipation rating of 625 mW in a through-hole TO-92 package. The 2N4123-AP is classified as obsolete, making identification of functionally compatible substitute components necessary for ongoing design support, maintenance, and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) Max	200	mA
Voltage - Collector Emitter Breakdown (Max)	30	V
Vce Saturation (Max) @ Ib, Ic	300 mV @ 5 mA, 50 mA	—
Current - Collector Cutoff (Max)	50	nA
DC Current Gain (hFE) Min @ Ic, Vce	50 @ 2 mA, 1 V	—
Power - Max	625	mW
Frequency - Transition	250	MHz
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the 2N4123-AP is determined by electrical and mechanical compatibility across the following critical parameters:

Electrical Compatibility Criteria:

Transistor polarity (NPN type required)
Collector current rating (minimum 200 mA)
Collector-emitter breakdown voltage (minimum 30 V)
Vce saturation characteristics (300 mV @ 5 mA, 50 mA)
DC current gain (hFE) performance at specified operating points
Power dissipation capability (minimum 625 mW)
Transition frequency (minimum 250 MHz)

Mechanical Compatibility Criteria:

Through-hole mounting configuration
TO-92 package form factor (TO-226-3, TO-226AA)
Three-lead formed leads configuration

Environmental & Compliance Criteria:

Operating temperature range (-55°C to 150°C)
RoHS3 compliance
Moisture sensitivity level (MSL 1)

The 500-00001 from Parallax Inc. meets all substitution criteria with equal or superior electrical ratings and identical mechanical packaging.

Parameter Comparison

Parameter	2N4123-AP (Main Part)	500-00001 (Substitute)	Compatibility
Transistor Type	NPN	NPN	Match
Current - Collector (Ic) Max	200 mA	200 mA	Match
Voltage - Collector Emitter Breakdown (Max)	30 V	40 V	Substitute Superior
Vce Saturation (Max) @ Ib, Ic	300 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA	Match
Current - Collector Cutoff (Max)	50 nA	50 nA	Match
DC Current Gain (hFE) Min @ Ic, Vce	50 @ 2 mA, 1 V	100 @ 10 mA, 1 V	Substitute Superior
Power - Max	625 mW	1.5 W	Substitute Superior
Frequency - Transition	250 MHz	300 MHz	Substitute Superior
Operating Temperature Range	-55 to 150°C	-55 to 150°C	Match
Mounting Type	Through Hole	Through Hole	Match
Package / Case	TO-92-3 (TO-226AA)	TO-92-3 (TO-226AA)	Match

Engineering Selection Recommendations

The 500-00001 from Parallax Inc. is a direct functional substitute for the obsolete 2N4123-AP. The substitute part maintains electrical equivalence across all critical parameters while providing superior performance margins in collector-emitter breakdown voltage (40 V vs. 30 V), DC current gain (100 vs. 50), power dissipation (1.5 W vs. 625 mW), and transition frequency (300 MHz vs. 250 MHz).

The 500-00001 is classified as an active product, ensuring ongoing availability and supply chain continuity. Both parts share identical mechanical packaging (TO-92 through-hole configuration), enabling direct pin-compatible replacement without circuit board modifications.

Compliance status: The 500-00001 maintains RoHS3 compliance and MSL 1 rating, consistent with the original 2N4123-AP specifications. Both devices operate across the full temperature range of -55°C to 150°C.

Frequently Asked Questions (FAQ)

Q: Can the 500-00001 be used as a direct replacement for the 2N4123-AP in existing designs?

A: Yes. The 500-00001 is pin-compatible and electrically equivalent. All critical electrical parameters (collector current, breakdown voltage, saturation characteristics, and current gain) meet or exceed the 2N4123-AP specifications. No circuit modifications are required.

Q: What are the key differences between these two parts?

A: The 500-00001 provides superior performance across four parameters: collector-emitter breakdown voltage (40 V vs. 30 V), DC current gain (100 vs. 50), power dissipation (1.5 W vs. 625 mW), and transition frequency (300 MHz vs. 250 MHz). The 2N4123-AP is obsolete; the 500-00001 is an active product.

Q: Are the packages identical?

A: Yes. Both parts use the TO-92-3 (TO-226AA) through-hole package with formed leads. Pin assignments and physical dimensions are compatible.

Q: Does the substitute part meet the same compliance requirements?

A: Yes. The 500-00001 is RoHS3 compliant with MSL 1 rating, matching the 2N4123-AP specifications.

Q: What is the operating temperature range for both parts?

A: Both the 2N4123-AP and 500-00001 operate across -55°C to 150°C junction temperature.

Q: Are there any electrical parameters where the 2N4123-AP performs better than the 500-00001?

A: No. The 500-00001 meets or exceeds all electrical specifications of the 2N4123-AP.

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