2N3906 PNP Bipolar Junction Transistor Equivalent & Substitute Parts

Part Overview

The 2N3906 is a PNP bipolar junction transistor manufactured by STMicroelectronics, rated for 40 V collector-emitter breakdown voltage and 200 mA maximum collector current. The device is packaged in a TO-92 through-hole configuration and is classified as obsolete product status. Due to its obsolete classification, equivalent and substitute parts from active manufacturers are necessary to maintain design continuity and ensure long-term component availability for new production and field replacements.

Key Parameters

Parameter	Value	Unit
Transistor Type	PNP	—
Current - Collector (Ic) Max	200	mA
Voltage - Collector Emitter Breakdown (Max)	40	V
Vce Saturation (Max) @ Ib, Ic	400 mV @ 5 mA, 50 mA	—
DC Current Gain (hFE) Min @ Ic, Vce	100 @ 10 mA, 1 V	—
Power - Max	625	mW
Frequency - Transition	250	MHz
Mounting Type	Through Hole	—
Package / Case	TO-92-3 (TO-226AA)	—
Operating Temperature Range	Up to 150	°C (TJ)

Substitute Part Grouping Explanation

Substitution of the 2N3906 is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Transistor Type: PNP (mandatory)
Collector-Emitter Breakdown Voltage: 40 V (minimum requirement)
Maximum Collector Current: 200 mA (minimum requirement)
Package Type: TO-92 through-hole (mechanical compatibility)
DC Current Gain (hFE): 100 @ 10 mA, 1 V (functional equivalence)
Power Dissipation: 625 mW (thermal capability)
Transition Frequency: 250 MHz (switching performance)

Substitution Categories:

Direct Equivalents meet all primary criteria without deviations:

2N3906BU (Fairchild Semiconductor)
2N3906TAR (onsemi)
2N3906-G (Comchip Technology)

Similar Substitutes meet core electrical requirements with specified parameter variations:

2N4403BU (Fairchild Semiconductor) — Higher collector current rating (600 mA) and lower transition frequency (200 MHz)
2N4058 PBFREE (Central Semiconductor Corp) — Lower collector-emitter breakdown voltage (30 V) and different saturation characteristics

Parameter Comparison

Parameter	2N3906 (STMicroelectronics)	2N3906BU (Fairchild)	2N3906TAR (onsemi)	2N3906-G (Comchip)	2N4403BU (Fairchild)	2N4058 PBFREE (Central Semi)
Product Status	Obsolete	Active	Active	Active	Active	Active
Transistor Type	PNP	PNP	PNP	PNP	PNP	PNP
Ic (Max) [mA]	200	200	200	200	600	200
Vce Breakdown (Max) [V]	40	40	40	40	40	30
Vce Saturation (Max) [mV]	400 @ 5 mA, 50 mA	400 @ 5 mA, 50 mA	400 @ 5 mA, 50 mA	400 @ 5 mA, 50 mA	750 @ 50 mA, 500 mA	700 @ 500 µA, 10 mA
hFE (Min) @ Ic, Vce	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	100 @ 10 mA, 1 V	30 @ 100 mA, 1 V	100 @ 150 mA, 2 V	100 @ 100 µA, 5 V
Power - Max [mW]	625	625	625	Not specified	625	625
Frequency - Transition [MHz]	250	250	250	250	200	Not specified
Operating Temperature [°C]	Up to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-65 to 150
Package / Case	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3	TO-92-3
RoHS Status	ROHS3 Compliant	Not specified	ROHS3 Compliant	ROHS3 Compliant	Not specified	ROHS3 Compliant
REACH Status	REACH Unaffected	Not specified	REACH Unaffected	REACH Unaffected	Not specified	REACH Unaffected

Engineering Selection Recommendations

For Direct Replacement (Pin-Compatible, Electrically Equivalent):

Select 2N3906BU, 2N3906TAR, or 2N3906-G when the application requires exact electrical and thermal performance matching. All three parts are active products with ROHS3 compliance and REACH unaffected status. 2N3906BU (Fairchild Semiconductor) offers the highest inventory availability (50,200 pcs). 2N3906TAR (onsemi) is supplied in cut tape packaging suitable for automated assembly. 2N3906-G (Comchip Technology) is available in bag packaging.

For Higher Current Applications:

Select 2N4403BU when the circuit requires collector current capability up to 600 mA while maintaining 40 V breakdown voltage. This part accepts higher base drive currents and exhibits higher saturation voltage (750 mV vs. 400 mV). Transition frequency is reduced to 200 MHz. This substitution is suitable only when the application can tolerate these parameter variations.

For Lower Voltage Applications:

Select 2N4058 PBFREE when the circuit operates at collector-emitter voltages not exceeding 30 V. This part maintains 200 mA collector current and 625 mW power dissipation. Saturation characteristics differ significantly (700 mV @ 500 µA, 10 mA). This substitution is suitable only when voltage headroom permits the 30 V maximum rating.

Compliance Considerations:

All active substitute parts maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment with current manufacturing standards. The 2N3906 original part is classified as obsolete; therefore, transition to an active substitute is necessary for new production designs.

Frequently Asked Questions (FAQ)

Q: Can 2N3906BU be used as a direct replacement for 2N3906?

A: Yes. 2N3906BU meets all electrical specifications of the 2N3906, including 40 V breakdown voltage, 200 mA collector current, 625 mW power dissipation, 250 MHz transition frequency, and 100 hFE minimum gain. The TO-92-3 package is mechanically identical. Pin configuration is unchanged.

Q: What is the difference between 2N3906-G and 2N3906BU?

A: Both parts are direct electrical equivalents with identical breakdown voltage, collector current, power rating, and transition frequency. The primary difference is manufacturer (Comchip Technology vs. Fairchild Semiconductor) and packaging format (bag vs. bulk). DC current gain specification differs: 2N3906-G specifies 30 hFE minimum @ 100 mA, 1 V, while 2N3906BU specifies 100 hFE minimum @ 10 mA, 1 V. Both exceed the 2N3906 requirement of 100 hFE @ 10 mA, 1 V.

Q: When should 2N4403BU be selected instead of 2N3906?

A: 2N4403BU is selected when the circuit requires collector current up to 600 mA. The 2N3906 is limited to 200 mA. Both parts share 40 V breakdown voltage and 625 mW power dissipation. However, 2N4403BU exhibits higher saturation voltage (750 mV vs. 400 mV) and lower transition frequency (200 MHz vs. 250 MHz). Selection requires verification that the application can tolerate these differences.

Q: Is 2N4058 PBFREE a suitable substitute for 2N3906?

A: 2N4058 PBFREE is a similar substitute with reduced voltage rating (30 V vs. 40 V). It maintains 200 mA collector current and 625 mW power dissipation. Saturation voltage is higher (700 mV @ 500 µA, 10 mA vs. 400 mV @ 5 mA, 50 mA). This part is suitable only for applications where the collector-emitter voltage does not exceed 30 V and where higher saturation voltage is acceptable.

Q: Are all substitute parts available in TO-92 packaging?

A: Yes. All listed substitute parts are packaged in TO-92-3 (TO-226AA) through-hole configuration, ensuring mechanical compatibility with 2N3906 footprints. Packaging format (bag, bulk, cut tape) varies by manufacturer and supplier but does not affect electrical performance or pin configuration.

Q: What is the operating temperature range difference between 2N3906 and its substitutes?

A: The 2N3906 specifies operation up to 150°C junction temperature without a lower limit. Active substitutes specify -55°C to 150°C (2N3906BU, 2N3906TAR, 2N4403BU) or -65°C to 150°C (2N4058 PBFREE, 2N3906-G). All substitutes support the 2N3906 upper temperature limit and extend the lower operating range.

Q: Are there RoHS and REACH compliance differences between substitute parts?

A: 2N3906BU and 2N4403BU do not specify RoHS or REACH status in available documentation. 2N3906TAR, 2N3906-G, and 2N4058 PBFREE are confirmed ROHS3 compliant and REACH unaffected. For applications requiring documented compliance, select parts with explicit certification statements.

Q: What is the significance of the "PBFREE" designation in 2N4058 PBFREE?

A: PBFREE indicates lead-free solder compatibility, confirming the part meets RoHS requirements for elimination of lead in electronic components. This designation ensures the part is suitable for lead-free assembly processes.

Q: Can 2N3906TAR be used in automated pick-and-place assembly?

A: Yes. 2N3906TAR is supplied in cut tape (CT) packaging, which is the standard format for automated component placement equipment. The part maintains identical electrical specifications and TO-92-3 package configuration as other substitutes.

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