2N3904CTA Equivalent & Substitute Parts

Part Overview

The 2N3904CTA is a through-hole NPN bipolar junction transistor manufactured by onsemi, rated for 40 V collector-emitter breakdown voltage and 200 mA maximum collector current. This device is classified as obsolete and operates across a temperature range of -55°C to 150°C. The 2N3904CTA is based on the 2N3904 base product number, a widely used general-purpose NPN transistor for low-signal amplification and switching applications.

Due to its obsolete product status, locating the 2N3904CTA for new designs or production runs presents supply chain challenges. Active equivalent and substitute parts are available from the same manufacturer and alternative sources, offering identical or superior electrical characteristics while maintaining through-hole TO-92-3 package compatibility.

Key Parameters

Parameter	Value	Unit
Transistor Type	NPN	—
Voltage - Collector Emitter Breakdown (Max)	40	V
Current - Collector (Ic) (Max)	200	mA
Power - Max	625	mW
Frequency - Transition	300	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 1V	—
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	—
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—

Substitute Part Grouping Explanation

Substitution of the 2N3904CTA is determined by strict equivalence across the following electrical and mechanical parameters:

Primary Substitution Criteria:

Transistor Type: NPN
Voltage - Collector Emitter Breakdown (Max): 40 V
Current - Collector (Ic) (Max): 200 mA
DC Current Gain (hFE) (Min) @ Ic, Vce: 100 @ 10mA, 1V
Vce Saturation (Max) @ Ib, Ic: 300mV @ 5mA, 50mA
Operating Temperature Range: -55°C to 150°C
Mounting Type: Through Hole
Package / Case: TO-92-3 (TO-226AA) Formed Leads

Direct Equivalents are onsemi manufactured parts with identical electrical specifications and active product status: 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR. These parts differ only in packaging format (Cut Tape) and compliance certifications, maintaining full electrical and thermal equivalence.

Cross-Manufacturer Equivalent is the 2N3904-AP from Micro Commercial Co, which meets all primary electrical criteria with minor variations in transition frequency (250 MHz versus 300 MHz) and Vce saturation specification (400mV versus 300mV), classified as obsolete.

Similar Part is the Parallax Inc. 500-00001, which matches all primary electrical parameters and transition frequency but features enhanced power dissipation capability (1.5 W versus 625 mW) and includes specified collector cutoff current (50nA).

Parameter Comparison

Parameter	2N3904CTA	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
Voltage - Collector Emitter Breakdown (Max)	40 V	40 V	40 V	40 V	40 V	40 V	40 V
Current - Collector (Ic) (Max)	200 mA	200 mA	200 mA	200 mA	200 mA	200 mA	200 mA
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
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 1V	100 @ 10mA, 1V	100 @ 10mA, 1V	100 @ 10mA, 1V	100 @ 10mA, 1V	100 @ 10mA, 1V	100 @ 10mA, 1V
Vce Saturation (Max) @ Ib, Ic	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	400mV @ 5mA, 50mA	300mV @ 5mA, 50mA
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C	-55 to 150°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	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 Active Parts):

The 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR are direct electrical equivalents manufactured by onsemi with active product status. These parts maintain identical electrical specifications to the 2N3904CTA across all critical parameters: 40 V breakdown voltage, 200 mA collector current, 300 MHz transition frequency, and 625 mW power dissipation. All four parts are ROHS3 compliant and REACH unaffected. Selection among these four parts is determined by packaging format and inventory availability rather than electrical performance. The 2N3904TA offers the highest inventory level (535,300 pieces), followed by 2N3904TAR (33,397 pieces), 2N3904TFR (22,042 pieces), and 2N3904TF (2,200 pieces).

Secondary Substitute (Cross-Manufacturer):

The 2N3904-AP from Micro Commercial Co is classified as obsolete and presents the same supply chain limitations as the original 2N3904CTA. While electrically compatible across primary parameters, this part exhibits reduced transition frequency (250 MHz versus 300 MHz) and higher Vce saturation voltage (400mV versus 300mV). This part is suitable only when onsemi active alternatives are unavailable and the application tolerates the specified performance variations.

Similar Alternative (Enhanced Power Capability):

The Parallax Inc. 500-00001 maintains electrical equivalence across all primary parameters and offers enhanced power dissipation capability (1.5 W versus 625 mW). This part includes specified collector cutoff current (50nA) and is active in production. The 500-00001 is suitable for applications requiring higher thermal headroom or where the enhanced power rating provides design margin.

Frequently Asked Questions (FAQ)

Q: Can the 2N3904TA directly replace the 2N3904CTA without circuit modification?

A: Yes. The 2N3904TA is electrically identical to the 2N3904CTA across all specified parameters: 40 V breakdown voltage, 200 mA collector current, 300 MHz transition frequency, 625 mW power dissipation, and -55°C to 150°C operating range. Both use the TO-92-3 package with formed leads. No circuit modification is required.

Q: What is the difference between 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR?

A: These four onsemi parts are electrically identical. The differences are in packaging format (all are Cut Tape) and internal manufacturing codes. Selection is based on inventory availability and supplier preference. All four are ROHS3 compliant and active in production.

Q: Why does the 2N3904-AP have different specifications?

A: The 2N3904-AP is manufactured by Micro Commercial Co and exhibits two specification differences: transition frequency of 250 MHz (versus 300 MHz) and Vce saturation of 400mV (versus 300mV). These variations may affect high-frequency performance and switching speed. This part is also obsolete, presenting the same supply challenges as the original 2N3904CTA.

Q: Is the Parallax Inc. 500-00001 a suitable replacement?

A: The 500-00001 is electrically compatible across all primary parameters and offers enhanced power dissipation (1.5 W versus 625 mW). It is active in production and suitable for applications where higher thermal capability is beneficial. The TO-92-3 package is mechanically compatible.

Q: Are all substitute parts ROHS3 compliant?

A: The four onsemi active parts (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) are ROHS3 compliant. The 2N3904-AP is also ROHS3 compliant. RoHS status for the Parallax Inc. 500-00001 is not specified in the provided data.

Q: What is the inventory status of each substitute?

A: 2N3904TA: 535,300 pieces; 2N3904TAR: 33,397 pieces; 2N3904TFR: 22,042 pieces; 2N3904TF: 2,200 pieces; 2N3904-AP: 2,283 pieces; 500-00001: 784 pieces.

Q: Can I use these parts interchangeably in existing designs?

A: Yes, for designs currently using the 2N3904CTA. All substitute parts maintain the same TO-92-3 package pinout and electrical specifications. No PCB layout changes are required. For new designs, the onsemi active parts (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) are recommended due to active production status and ROHS3 compliance.

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