2N4401_D81Z Equivalent & Substitute Parts

Part Overview

The 2N4401_D81Z is a small-signal NPN bipolar junction transistor manufactured by onsemi, designed for general-purpose switching and amplification applications. This device features a maximum collector current of 600 mA, collector-emitter breakdown voltage of 40 V, and a transition frequency of 250 MHz, housed in a TO-92-3 through-hole package. The 2N4401_D81Z carries an obsolete product status, making identification of equivalent and substitute parts essential for ongoing design support and production continuity. Direct substitutes with active product status are available from the same manufacturer and alternative sources, offering identical electrical specifications and mechanical compatibility.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) Max	600	mA
Voltage - Collector Emitter Breakdown (Max)	40	V
Vce Saturation (Max) @ Ib, Ic	750 mV @ 50 mA, 500 mA	—
DC Current Gain (hFE) Min @ Ic, Vce	100 @ 150 mA, 1 V	—
Power - Max	625	mW
Frequency - Transition	250	MHz
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	—

Substitute Part Grouping Explanation

Substitution of the 2N4401_D81Z is determined by strict equivalence across the following electrical and mechanical parameters: transistor type (NPN), maximum collector current (600 mA), collector-emitter breakdown voltage (40 V), saturation voltage characteristics (750 mV @ 50 mA, 500 mA), minimum DC current gain (100 @ 150 mA, 1 V), maximum power dissipation (625 mW), transition frequency (250 MHz), operating temperature range (-55°C to 150°C), and through-hole mounting in TO-92-3 package configuration.

Substitute parts are classified into two categories:

Direct Substitutes (Identical Electrical and Mechanical Specifications): Parts meeting all specified parameters with active product status, including 2N4401TA, 2N4401TAR, and 2N4401TFR from onsemi, and 2N4401TF from Fairchild Semiconductor.

Similar Substitutes (Equivalent Electrical Performance with Minor Specification Variance): The 2N4401-AP from Micro Commercial Co maintains electrical equivalence with maximum power dissipation of 600 mW (versus 625 mW) and operates within the same temperature and voltage parameters, though carrying obsolete product status.

Parameter Comparison

Parameter	2N4401_D81Z	2N4401TA	2N4401TAR	2N4401TF	2N4401TFR	2N4401-AP
Manufacturer	onsemi	onsemi	onsemi	Fairchild Semiconductor	onsemi	Micro Commercial Co
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Ic (Max)	600 mA	600 mA	600 mA	600 mA	600 mA	600 mA
Vce Breakdown (Max)	40 V	40 V	40 V	40 V	40 V	40 V
Vce Saturation (Max)	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA	750 mV @ 50 mA, 500 mA
hFE (Min)	100 @ 150 mA, 1 V	100 @ 150 mA, 1 V	100 @ 150 mA, 1 V	100 @ 150 mA, 1 V	100 @ 150 mA, 1 V	100 @ 150 mA, 1 V
Power (Max)	625 mW	625 mW	625 mW	625 mW	625 mW	600 mW
Frequency - Transition	250 MHz	250 MHz	250 MHz	250 MHz	250 MHz	250 MHz
Operating Temperature	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
Package	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92
Product Status	Obsolete	Active	Active	Active	Active	Obsolete
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For applications requiring replacement of the obsolete 2N4401_D81Z, the following selection criteria apply:

Primary Substitutes (Active Product Status with Full Compliance): The 2N4401TA, 2N4401TAR, and 2N4401TFR from onsemi are recommended as primary substitutes. All three parts maintain identical electrical specifications, operate within the same temperature range, and carry ROHS3 compliance certification. These parts are available in active production status with substantial inventory levels, ensuring long-term supply continuity. The 2N4401TA and 2N4401TAR are supplied in cut-tape packaging, while 2N4401TFR is also available in cut-tape format.

Alternative Substitute (Cross-Manufacturer Option): The 2N4401TF from Fairchild Semiconductor provides electrical equivalence with identical performance parameters and through-hole TO-92-3 package compatibility. This part maintains active product status and is suitable for applications where multi-source qualification is required.

Secondary Substitute (Obsolete Status): The 2N4401-AP from Micro Commercial Co offers electrical compatibility with a minor power dissipation specification of 600 mW versus 625 mW. However, this part carries obsolete product status and should be selected only when existing inventory must be utilized or when design legacy requirements mandate its use.

Frequently Asked Questions (FAQ)

Q: Can the 2N4401TA directly replace the 2N4401_D81Z in existing designs?

A: Yes. The 2N4401TA is electrically and mechanically equivalent to the 2N4401_D81Z. Both parts share identical maximum collector current (600 mA), collector-emitter breakdown voltage (40 V), saturation voltage characteristics, DC current gain, power dissipation (625 mW), transition frequency (250 MHz), and operating temperature range (-55°C to 150°C). The TO-92-3 package pinout and lead configuration are identical, enabling direct substitution without circuit modification.

Q: What is the difference between 2N4401TA, 2N4401TAR, and 2N4401TFR?

A: All three parts are electrically identical and meet the same performance specifications. The primary differences are packaging format (all supplied in cut-tape) and manufacturer source. 2N4401TA and 2N4401TAR are onsemi products, while 2N4401TFR is also from onsemi. All three carry ROHS3 compliance and active product status. Selection between these parts is based on inventory availability and supply chain requirements rather than technical performance.

Q: Is the 2N4401TF from Fairchild Semiconductor a suitable substitute?

A: Yes. The 2N4401TF maintains all electrical specifications required for substitution, including 600 mA maximum collector current, 40 V breakdown voltage, 625 mW power dissipation, and 250 MHz transition frequency. The TO-92-3 package is mechanically compatible. This part is suitable for applications requiring cross-manufacturer qualification or when Fairchild Semiconductor sourcing is preferred.

Q: Can the 2N4401-AP be used as a substitute despite its obsolete status?

A: The 2N4401-AP is electrically compatible with the 2N4401_D81Z across all critical parameters except power dissipation, which is specified at 600 mW versus 625 mW. This 25 mW difference is negligible in most applications. However, the 2N4401-AP carries obsolete product status, making it unsuitable for new designs or long-term production. Use this part only when existing inventory must be consumed or when design legacy requirements mandate its selection.

Q: Are there any compliance or certification differences between substitute parts?

A: The onsemi parts (2N4401TA, 2N4401TAR, 2N4401TFR) carry ROHS3 compliance certification. The 2N4401-AP from Micro Commercial Co also carries ROHS3 compliance. All parts are REACH Unaffected and carry EAR99 export classification. The 2N4401TF from Fairchild Semiconductor does not specify RoHS status in the provided data. For applications requiring explicit ROHS3 compliance documentation, select from the onsemi or Micro Commercial Co options.

Q: What packaging formats are available for substitute parts?

A: All substitute parts are supplied in through-hole TO-92-3 package configuration with formed leads, matching the original 2N4401_D81Z package. The 2N4401TA, 2N4401TAR, and 2N4401TFR are available in cut-tape packaging format. The 2N4401TF packaging format is not specified in the provided data. The 2N4401-AP is supplied in cut-tape format. All parts are compatible with standard through-hole PCB assembly processes.

Q: Which substitute part offers the best long-term supply availability?

A: The 2N4401TA, 2N4401TAR, and 2N4401TFR from onsemi are recommended for long-term supply assurance, as all three carry active product status. The 2N4401TA maintains the highest inventory level at 89,662 pieces, followed by 2N4401TAR at 40,100 pieces and 2N4401TFR at 24,100 pieces. These parts are in active production and suitable for new designs requiring sustained component availability.

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