2N3904-AP Equivalent & Substitute Parts

Part Overview

The 2N3904-AP is a Bipolar (BJT) NPN transistor manufactured by Micro Commercial Co, rated for 40 V collector-emitter breakdown voltage and 200 mA maximum collector current. This device is packaged in a TO-92 through-hole configuration and is classified as obsolete. The 2N3904-AP is based on the 2N3904 base product number, a widely used general-purpose NPN transistor for low-signal amplification and switching applications.

Due to the obsolete product status of the 2N3904-AP, equivalent substitute parts are necessary to maintain design continuity and ensure component availability for production and repair applications. Active alternatives from onsemi provide direct functional equivalence while maintaining the same electrical specifications and package form factor.

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	250	MHz
DC Current Gain (hFE) (Min) @ Ic, Vce	100 @ 10mA, 1V	—
Vce Saturation (Max) @ Ib, Ic	400mV @ 5mA, 50mA	—
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitute parts for the 2N3904-AP are classified into two categories based on electrical and mechanical compatibility:

Direct Substitutes (onsemi Manufactured): Parts 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR are direct substitutes manufactured by onsemi. These parts maintain identical electrical specifications for collector-emitter breakdown voltage (40 V), maximum collector current (200 mA), DC current gain (100 @ 10mA, 1V), and operating temperature range (-55°C to 150°C). All direct substitutes are packaged in TO-92-3 configuration with formed leads, matching the mechanical requirements of the 2N3904-AP. The primary distinction among direct substitutes is product status (all active) and inventory availability. Direct substitutes feature improved transition frequency (300 MHz versus 250 MHz) and reduced Vce saturation (300 mV versus 400 mV), representing performance enhancements over the original part.

Similar Substitute (Parallax Inc. Manufactured): Part 500-00001 is classified as a similar substitute due to matching electrical parameters for collector-emitter breakdown voltage (40 V), maximum collector current (200 mA), DC current gain (100 @ 10mA, 1V), and operating temperature range (-55°C to 150°C). This part also features transition frequency of 300 MHz and Vce saturation of 300 mV. The 500-00001 differs in maximum power dissipation (1.5 W versus 625 mW) and includes specified collector cutoff current (50 nA). Package configuration remains TO-92 through-hole compatible.

Substitution eligibility is determined by matching the following critical parameters: transistor type (NPN), collector-emitter breakdown voltage (40 V), maximum collector current (200 mA), DC current gain minimum (100 @ 10mA, 1V), operating temperature range (-55°C to 150°C), and through-hole TO-92 package form factor.

Parameter Comparison

Parameter	2N3904-AP (Micro Commercial Co)	2N3904TA (onsemi)	2N3904TAR (onsemi)	2N3904TF (onsemi)	2N3904TFR (onsemi)	500-00001 (Parallax Inc.)
Transistor Type	NPN	NPN	NPN	NPN	NPN	NPN
Voltage - Collector Emitter Breakdown (Max)	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
Power - Max	625 mW	625 mW	625 mW	625 mW	625 mW	1.5 W
Frequency - Transition	250 MHz	300 MHz	300 MHz	300 MHz	300 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
Vce Saturation (Max) @ Ib, Ic	400mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA	300mV @ 5mA, 50mA
Operating Temperature Range	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads	TO-226-3, TO-92-3 (TO-226AA) Formed Leads
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	Not Specified
Product Status	Obsolete	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Primary Recommendation: The onsemi 2N3904TA, 2N3904TAR, 2N3904TF, and 2N3904TFR parts are the preferred substitutes for the obsolete 2N3904-AP. All four onsemi variants maintain active product status, ensuring long-term availability and supply chain continuity. These parts are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements. The onsemi substitutes provide enhanced electrical performance with transition frequency increased to 300 MHz and reduced Vce saturation voltage (300 mV), while maintaining identical critical specifications for breakdown voltage, collector current, and DC current gain.

Selection among the four onsemi variants (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) is determined by packaging designation and inventory requirements. All four parts are electrically identical and mechanically compatible. The 2N3904TA offers the highest inventory availability (535,300 pieces), followed by 2N3904TFR (22,042 pieces), 2N3904TAR (33,397 pieces), and 2N3904TF (2,200 pieces).

Secondary Recommendation: The Parallax Inc. 500-00001 is suitable as an alternative substitute where higher power dissipation capability (1.5 W) is beneficial. This part maintains all critical electrical parameters and through-hole TO-92 package compatibility. However, the 500-00001 does not carry specified RoHS3 compliance documentation and has lower inventory availability (784 pieces) compared to onsemi alternatives.

Frequently Asked Questions (FAQ)

Q: Can the 2N3904TA directly replace the 2N3904-AP without circuit modification?

A: Yes. The 2N3904TA maintains identical electrical specifications for collector-emitter breakdown voltage (40 V), maximum collector current (200 mA), DC current gain (100 @ 10mA, 1V), and operating temperature range (-55°C to 150°C). The TO-92-3 package with formed leads is mechanically compatible with the original 2N3904-AP. The improved transition frequency (300 MHz versus 250 MHz) and reduced Vce saturation (300 mV versus 400 mV) represent performance enhancements that do not require circuit redesign.

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

A: These four onsemi parts are electrically and mechanically identical. The differences are in packaging designation and inventory levels. All four parts feature the same electrical specifications, transition frequency (300 MHz), and Vce saturation (300 mV). Selection is based on packaging preference and component availability from your supplier.

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

A: The 500-00001 is electrically compatible with the 2N3904-AP for applications requiring the specified electrical parameters. The primary advantage is higher maximum power dissipation (1.5 W versus 625 mW). However, RoHS3 compliance is not specified for this part. The onsemi alternatives are recommended for applications requiring documented environmental compliance.

Q: Does the improved transition frequency (300 MHz) of substitute parts affect circuit operation?

A: The increased transition frequency of substitute parts (300 MHz versus 250 MHz) represents improved high-frequency performance. This enhancement does not negatively affect circuit operation in applications designed for the original 250 MHz specification. Circuits operate within the enhanced performance envelope of the substitute parts.

Q: Are all substitute parts RoHS3 compliant?

A: The four onsemi substitutes (2N3904TA, 2N3904TAR, 2N3904TF, 2N3904TFR) are ROHS3 compliant. The Parallax Inc. 500-00001 does not specify RoHS3 compliance status. For applications requiring documented RoHS3 compliance, the onsemi alternatives are the appropriate selection.

Q: What is the significance of the reduced Vce saturation voltage in substitute parts?

A: The substitute parts feature Vce saturation of 300 mV compared to 400 mV in the original 2N3904-AP. This 100 mV reduction represents improved saturation characteristics, resulting in lower power dissipation during switching operation and improved switching speed. This enhancement is beneficial for switching applications and does not require circuit modification.

Q: Can I use the 500-00001 in high-temperature applications?

A: Yes. The 500-00001 maintains the same operating temperature range as the 2N3904-AP (-55°C to 150°C junction temperature), making it suitable for high-temperature applications within this specification.

Q: Which substitute part should I select for new production designs?

A: The 2N3904TA is recommended for new production designs due to highest inventory availability (535,300 pieces), active product status, ROHS3 compliance, and electrical performance enhancement. This selection ensures supply chain continuity and regulatory compliance.

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