2N3905_D29Z Equivalent & Substitute Parts

Part Overview

The 2N3905_D29Z is a PNP bipolar junction transistor manufactured by onsemi, rated for 40 V collector-emitter breakdown voltage and 200 mA maximum collector current in a TO-92-3 through-hole package. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. The 2N3905 series remains widely used in legacy applications and educational circuits, requiring reliable alternatives for replacement and new production builds.

Substiute Parts

2N3905_D29Z

onsemiIn Stock: 9452N3905_D29Z Datasheet

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2N3906-AP

Micro Commercial CoIn Stock: 13742N3906-AP Datasheet

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2N4403-AP

Micro Commercial CoIn Stock: 15682N4403-AP Datasheet

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ZTX549STZ

Diodes IncorporatedIn Stock: 20247ZTX549STZ Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the 2N3905_D29Z is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Transistor Type: PNP (required)
• Voltage - Collector Emitter Breakdown (Max): 40 V or greater (required)
• Current - Collector (Ic) (Max): 200 mA or greater (required)
• Mounting Type: Through Hole (required)
• Package / Case: TO-92-3 or TO-92 compatible form factor (required)
• Operating Temperature Range: Must encompass -55°C to 150°C minimum (required)

Secondary Compatibility Parameters:

• Vce Saturation: Lower or equal values preferred for switching applications
• DC Current Gain (hFE): Minimum 50 @ specified conditions
• Power Dissipation: 600 mW or greater

Substitute parts are grouped into two categories based on electrical performance alignment:

Category A - Direct Electrical Equivalents: Parts matching all primary criteria with identical or superior electrical specifications within the same voltage and current ratings (2N3906-AP, 2N4403-AP).

Category B - Enhanced Performance Alternatives: Parts exceeding primary specifications in current capacity or power dissipation while maintaining voltage compatibility and through-hole packaging (ZTX549STZ).

Parameter Comparison

Engineering Selection Recommendations

2N3906-AP (Micro Commercial Co)

The 2N3906-AP is a direct electrical equivalent to the 2N3905_D29Z with identical voltage and current ratings. Both parts share the same 40 V breakdown voltage, 200 mA collector current maximum, and TO-92-3 package form factor. The 2N3906-AP provides superior DC current gain (100 vs. 50 minimum) and includes transition frequency specification (250 MHz). This part is ROHS3 compliant and maintains the same operating temperature range. Selection of 2N3906-AP is appropriate for direct replacement in existing designs with no circuit modifications required.

2N4403-AP (Micro Commercial Co)

The 2N4403-AP meets all primary substitution criteria with 40 V breakdown voltage and TO-92-3 package compatibility. This part differs in saturation voltage specification (750 mV vs. 400 mV) and is rated for higher collector current conditions (500 mA test point vs. 50 mA). The 2N4403-AP includes cutoff current specification (100 nA ICBO) and transition frequency (200 MHz). ROHS3 compliance and identical operating temperature range support its use as a substitute. Circuit performance may differ in saturation-mode applications due to higher Vce saturation characteristics.

ZTX549STZ (Diodes Incorporated)

The ZTX549STZ is an active-status alternative with enhanced electrical performance. This part exceeds the 2N3905_D29Z in current capacity (1 A vs. 200 mA) and power dissipation (1 W vs. 625 mW). The voltage rating is reduced to 30 V, which limits application to circuits operating below 30 V. The E-Line-3 package is mechanically compatible with TO-92 form factors. Extended operating temperature range (-55 to 200°C) and active product status provide long-term availability. Selection of ZTX549STZ is appropriate for applications requiring higher current capacity within voltage constraints and where long-term supply continuity is critical.

Frequently Asked Questions (FAQ)

Q: Can the 2N3906-AP be used as a direct replacement for the 2N3905_D29Z?

A: Yes. Both parts are PNP transistors with identical 40 V breakdown voltage, 200 mA maximum collector current, and TO-92-3 package. The 2N3906-AP provides equal or superior electrical performance with no circuit modifications required.

Q: What is the primary difference between the 2N4403-AP and the 2N3905_D29Z?

A: The 2N4403-AP has a higher saturation voltage (750 mV vs. 400 mV) and is specified at higher collector current test points. Both share the same 40 V voltage rating and 200 mA current limit. The 2N4403-AP is suitable for applications where saturation voltage differences do not affect circuit operation.

Q: Why is the ZTX549STZ rated for only 30 V when the 2N3905_D29Z is rated for 40 V?

A: The ZTX549STZ is a different device with enhanced current capacity (1 A vs. 200 mA) and power handling (1 W vs. 625 mW). The lower voltage rating reflects its design specifications. Use ZTX549STZ only in circuits operating at 30 V or below.

Q: Are all substitute parts available in the same TO-92-3 package?

A: The 2N3906-AP and 2N4403-AP are available in TO-92-3 packages. The ZTX549STZ uses an E-Line-3 package, which is mechanically compatible with TO-92 form factors and fits the same through-hole footprints.

Q: Which substitute part has the longest product lifecycle?

A: The ZTX549STZ is classified as active product status, indicating ongoing manufacturing and availability. The 2N3906-AP and 2N4403-AP are obsolete. For new designs requiring long-term supply assurance, the ZTX549STZ is the preferred choice.

Q: Can the ZTX549STZ be used in all applications designed for the 2N3905_D29Z?

A: The ZTX549STZ can be used in applications where the circuit operates at 30 V or below. Circuits designed for 40 V operation cannot use the ZTX549STZ due to its lower voltage rating. Verify circuit maximum voltage before substitution.

Q: What is the significance of the DC Current Gain (hFE) difference between these parts?

A: The 2N3905_D29Z has a minimum hFE of 50, while the 2N3906-AP and 2N4403-AP have minimum hFE of 100. Higher current gain reduces base drive requirements in amplifier circuits. Circuits designed for hFE of 50 will operate with improved performance using higher-gain substitutes.

Q: Are all substitute parts RoHS compliant?

A: The 2N3906-AP and 2N4403-AP are ROHS3 compliant. The 2N3905_D29Z is REACH unaffected. The ZTX549STZ is ROHS3 compliant. Verify compliance requirements for your specific application and regulatory jurisdiction.