2N3904_D81Z Equivalent & Substitute Parts

Part Overview

The 2N3904_D81Z is a Bipolar (BJT) NPN transistor manufactured by onsemi, rated for 40 V collector-emitter breakdown voltage and 200 mA maximum collector current. This device is packaged in TO-92-3 (TO-226AA) formed leads configuration and is designed for through-hole mounting applications. The part is classified as Obsolete, making identification of equivalent and substitute parts essential for ongoing design support and production continuity.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Current - Collector (Ic) (Max)	200	mA
Voltage - Collector Emitter Breakdown (Max)	40	V
Vce Saturation (Max) @ Ib, Ic	300 mV @ 5 mA, 50 mA	—
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10 mA, 1 V	—
Power - Max	625	mW
Frequency - Transition	300	MHz
Operating Temperature	-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 2N3904_D81Z is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Transistor Type: NPN
Current - Collector (Ic) (Max): 200 mA
Voltage - Collector Emitter Breakdown (Max): 40 V
DC Current Gain (hFE) (Min) @ Ic, Vce: 100 @ 10 mA, 1 V
Operating Temperature Range: -55°C to 150°C (TJ)
Mounting Type: Through Hole
Package / Case: TO-92-3 (TO-226AA) Formed Leads

Direct Substitutes (onsemi): The following onsemi part numbers meet all electrical and mechanical parameters of the 2N3904_D81Z:

2N3904TA
2N3904TAR
2N3904TF
2N3904TFR

These parts are classified as Active products with ROHS3 compliance, providing superior availability and regulatory status compared to the Obsolete main part.

Cross-Manufacturer Substitute: The 2N3904-AP (Micro Commercial Co) meets all primary electrical parameters with identical collector current, breakdown voltage, and current gain specifications. This part is classified as Obsolete.

Similar Part (Extended Capability): The 500-00001 (Parallax Inc.) meets all primary electrical parameters and offers increased power dissipation (1.5 W versus 625 mW) and specified collector cutoff current (50 nA). This part is classified as Active.

Parameter Comparison

Parameter	2N3904_D81Z	2N3904TA	2N3904TAR	2N3904TF	2N3904TFR	2N3904-AP	500-00001
Manufacturer	onsemi	onsemi	onsemi	onsemi	onsemi	Micro Commercial Co	Parallax Inc.
Product Status	Obsolete	Active	Active	Active	Active	Obsolete	Active
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN	NPN
Current - Collector (Ic) (Max)	200 mA	200 mA	200 mA	200 mA	200 mA	200 mA	200 mA
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	40 V	40 V	40 V	40 V
Vce Saturation (Max) @ Ib, Ic	300 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA	400 mV @ 5 mA, 50 mA	300 mV @ 5 mA, 50 mA
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V
Power - Max	625 mW	625 mW	625 mW	625 mW	625 mW	625 mW	1.5 W
Frequency - Transition	300 MHz	300 MHz	300 MHz	300 MHz	300 MHz	250 MHz	300 MHz
Operating Temperature	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)	-55 to 150 °C (TJ)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3	TO-226-3, TO-92-3
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not specified
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	REACH Unaffected	Not specified

Engineering Selection Recommendations

Primary Substitutes (onsemi 2N3904 Series - Active Status):

The onsemi part numbers 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR are direct electrical and mechanical equivalents to the 2N3904_D81Z. All four parts are classified as Active products with ROHS3 compliance, ensuring long-term availability and regulatory alignment. These parts are packaged in Cut Tape (CT) format and are suitable for automated assembly processes. Selection among these four Active variants should be based on packaging format requirements and inventory availability.

Cross-Manufacturer Substitute (Micro Commercial Co 2N3904-AP):

The 2N3904-AP meets all primary electrical specifications and maintains identical package configuration. However, this part is classified as Obsolete, presenting the same long-term availability concerns as the main part. The Vce saturation specification differs slightly (400 mV versus 300 mV), which may affect circuit performance in saturation-mode applications. This part should be considered only when onsemi alternatives are unavailable.

Extended-Capability Alternative (Parallax Inc. 500-00001):

The 500-00001 provides all required electrical parameters with enhanced power dissipation capability (1.5 W versus 625 mW) and specified collector cutoff current. This part is classified as Active, providing superior availability. The increased power rating allows operation in higher-dissipation applications without thermal derating. This part is suitable for designs requiring enhanced thermal margin or higher power handling.

Regulatory and Compliance Considerations:

All onsemi Active variants (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) carry ROHS3 compliance certification, meeting current environmental regulations. All parts maintain REACH Unaffected status. For new designs and production continuity, selection of Active-status parts is strongly supported by regulatory compliance and long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can the 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR be used interchangeably with the 2N3904_D81Z?

A: Yes. These four onsemi part numbers are direct electrical and mechanical equivalents. All meet identical specifications for collector current (200 mA), breakdown voltage (40 V), current gain (100 @ 10 mA, 1 V), power dissipation (625 mW), transition frequency (300 MHz), and operating temperature range (-55°C to 150°C). All are packaged in TO-92-3 (TO-226AA) formed leads for through-hole mounting. The primary difference is packaging format (Cut Tape) and Active product status, which improves availability.

Q: What is the difference between the onsemi Active variants and the 2N3904-AP?

A: The onsemi variants (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) are classified as Active products with ROHS3 compliance, ensuring long-term supply and regulatory alignment. The 2N3904-AP (Micro Commercial Co) is classified as Obsolete and exhibits a higher Vce saturation specification (400 mV versus 300 mV), which may affect saturation-mode circuit performance. The onsemi variants are preferred for new designs and production continuity.

Q: Can the Parallax Inc. 500-00001 replace the 2N3904_D81Z in all applications?

A: The 500-00001 meets all primary electrical parameters and maintains identical package configuration. The key difference is enhanced power dissipation (1.5 W versus 625 mW), which provides additional thermal margin. This part is suitable for applications requiring higher power handling or thermal headroom. The part is classified as Active, providing superior long-term availability.

Q: What packaging formats are available for the onsemi substitutes?

A: The onsemi Active variants (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) are supplied in Cut Tape (CT) packaging format, suitable for automated assembly processes. All maintain the TO-92-3 (TO-226AA) formed leads physical configuration for through-hole mounting. The main part 2N3904_D81Z does not specify a packaging format in the provided data.

Q: Are there any electrical performance differences between the onsemi Active variants?

A: No. The 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR are electrically identical. All meet the same specifications for current, voltage, gain, power, and frequency. Selection among these variants should be based on packaging availability, supplier inventory, and procurement lead times.

Q: What is the significance of the Vce saturation difference in the 2N3904-AP?

A: The 2N3904-AP specifies 400 mV Vce saturation compared to 300 mV for the 2N3904_D81Z and onsemi variants. In saturation-mode applications (such as switching circuits), this 100 mV difference results in higher voltage drop across the transistor, increasing power dissipation and reducing switching efficiency. For linear amplification applications, this difference is typically negligible.

Q: Is the 500-00001 suitable for high-frequency applications?

A: Yes. The 500-00001 maintains the same transition frequency specification (300 MHz) as the 2N3904_D81Z and onsemi variants. The enhanced power rating does not compromise high-frequency performance. This part is suitable for RF and high-frequency switching applications requiring additional thermal margin.

Q: What compliance certifications should I verify for production use?

A: For new production designs, verify ROHS3 compliance and REACH Unaffected status. The onsemi Active variants (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) carry both certifications. The 2N3904-AP carries ROHS3 compliance but is Obsolete. The 500-00001 compliance status is not fully specified in the provided data. Consult manufacturer datasheets for complete regulatory documentation.

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