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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

Microchip Technology 2N2905A

Name: 2N2905A
Brand: Microchip Technology
SKU: 2N2905A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N2905A

Manufacturer:: Microchip Technology

Category:: Single Bipolar Transistors

Package:: TO-205AD, TO-39-3 Metal Can

Datasheet:: 2N2905A.pdf

Description:: TRANS PNP 60V 0.6A TO39

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N2905A from STMicroelectronics is a silicon planar epitaxial PNP bipolar junction transistor in TO-39 metal package, rated for −60 V V_CEO, −0.6 A I_C, and 0.6 W total dissipation at T_amb ≤ 25 °C. It delivers h_FE ≥ 75 at I_C = −0.1 mA and supports high-speed saturated switching in discrete power control stages.

For engineers reviewing the 2N2905A datasheet, 2N2905A pinout, 2N2905A application, or 2N2905A equivalent, key selection criteria include verified V_CEO/V_CBO breakdown ratings, measured t_d/t_r/t_s/t_f switching times, thermal resistance (R_thj-case = 50 °C/W), and TO-39 mechanical compatibility with legacy through-hole PCB layouts.

Technical Context

This PNP BJT operates in active, saturation, and cutoff regions with defined DC gain (h_FE) across five collector current points from −0.1 mA to −500 mA. Its switching performance is characterized under pulsed conditions (300 µs, ≤1% duty cycle) with specified delay (10 ns), rise (40 ns), storage (80 ns), and fall (30 ns) times.

The device uses a metal-can TO-39 package with direct case thermal path, enabling junction-to-case thermal resistance of 50 °C/W. Absolute maximum ratings include −60 V collector-base and collector-emitter voltages, −5 V emitter-base voltage, and 175 °C maximum junction temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−60 V - Maximum safe collector-emitter voltage with base open; defines off-state blocking capability in switch applications.
I_C	−0.6 A - Continuous DC collector current rating; sets upper limit for steady-state load drive in linear or switching configurations.
P_tot	0.6 W at T_amb ≤ 25 °C - Total power dissipation limit; requires derating above ambient temperature per R_thj-amb = 250 °C/W.
h_FE	75–300 - DC current gain range across I_C = −0.1 mA to −500 mA; determines required base drive for target collector current.
t_s	80 ns - Storage time under V_CC = −6 V, I_C = −150 mA, I_B1 = −I_B2 = −15 mA; critical for turn-off speed in saturated switching.
f_T	200 MHz - Transition frequency at V_CE = −20 V, I_C = −50 mA; indicates usable bandwidth in small-signal amplification.
R_thj-case	50 °C/W - Junction-to-case thermal resistance; enables direct heatsinking via metal can for improved thermal management.

Pinout & Package

2N2905A is housed in a hermetically sealed TO-39 metal package with three leads: Emitter (E), Base (B), and Collector (C). The case serves as the collector terminal, providing low-inductance, low-thermal-resistance connection to heatsinks or ground planes.

Pin/Terminal	Circuit Role	Design Meaning
Case / Can	Collector (C)	Electrically connected to collector; provides primary thermal conduction path and mechanical mounting surface.
Lead 1 (shorter)	Emitter (E)	Current exit terminal in PNP operation; typically tied to higher potential rail in switching circuits.
Lead 2 (longer)	Base (B)	Control terminal; negative base current required to forward-bias BE junction and enable conduction.

Key Features

Feature	Design Value
High-voltage PNP switching	Rated for −60 V V_CEO and V_CBO, supporting robust operation in industrial relay drivers and power supply feedback loops.
Verified switching timing	Documented t_d = 10 ns, t_r = 40 ns, t_s = 80 ns, t_f = 30 ns under standardized test conditions for predictable digital interface design.
TO-39 metal-can package	Provides R_thj-case = 50 °C/W and mechanical ruggedness for high-reliability environments including aerospace and military-grade assemblies.
Wide h_FE range	DC gain from 75 to 300 across I_C = −0.1 mA to −500 mA enables flexible biasing in both low-current sensing and medium-power drive stages.

Applications

Relay Driver Stage

Linear Voltage Regulator Pass Element

Use Scenario: Driving electromagnetic relays requiring >100 mA coil current in industrial PLC output modules.

IC Role / Device Role / Timing Role: PNP switch controlling relay coil current path between +V_CC and ground; operates in saturation during ON state.

Use Value: −60 V V_CEO withstands inductive kickback; 80 ns storage time ensures fast release without contact chatter.

Use Scenario: Acting as series pass transistor in adjustable linear regulators delivering up to 500 mA output current.

IC Role / Device Role / Timing Role: Current-controlled linear amplifier regulating output voltage via base-emitter bias network.

Use Value: h_FE ≥ 100 at I_C = −10 mA ensures stable loop gain; R_thj-case = 50 °C/W supports heatsink integration for thermal stability.

Discrete Logic Level Shifter

Analog Signal Inverter

Use Scenario: Converting 3.3 V logic signals to −5 V or −12 V levels for interfacing with legacy TTL or ECL systems.

IC Role / Device Role / Timing Role: Common-emitter inverter stage with fixed bias; transitions between cutoff and saturation based on input logic level.

Use Value: Verified t_r/t_f < 50 ns enables reliable operation up to 5 MHz; −5 V V_EBO rating protects against reverse base-emitter stress.

Use Scenario: Inverting analog sensor signals (e.g., thermistor bridge outputs) in precision instrumentation front-ends.

IC Role / Device Role / Timing Role: Active-load common-emitter amplifier operating in active region with emitter degeneration resistor.

Use Value: f_T = 200 MHz supports bandwidth >10 MHz at moderate gain; low C_CB0 = 8 pF minimizes Miller effect distortion.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP switching transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N2907A	TO-18 package (R_thj-amb = 375 °C/W), lower P_tot = 0.4 W, identical electrical specs except reduced thermal capability.	Suitable for low-power, space-constrained PCBs where heatsinking is impractical.	Select when board area is limited and power dissipation remains below 300 mW.
MPSA92	TO-92 plastic package, V_CEO = −300 V, I_C = −0.5 A, h_FE = 25–200, no metal-can thermal path.	Used in high-voltage but low-current applications like CRT deflection circuits or photomultiplier bases.	Choose only if >−60 V blocking is required and TO-39 mounting is not feasible.

Compared with 2N2907A, the 2N2905A offers superior thermal performance and higher power handling due to its TO-39 metal can; versus MPSA92, it trades ultra-high voltage capability for better thermal reliability and tighter h_FE consistency at medium currents.

Availability

2N2905A is available at Aetrix Electronics and suitable for relay driver stages, linear voltage regulator pass elements, discrete logic level shifters, and analog signal inverters requiring stable component supply across industrial control, test equipment, and legacy system repair programs.

Supply support for 2N2905A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power discrete solutions.

The 2N2905A belongs to ST's legacy bipolar transistor product line, designed specifically for high-reliability through-hole switching and linear amplification in mission-critical analog and power systems.

FAQ

Is the 2N2905A pin-compatible with the 2N2907A?

No. Although electrically similar, the 2N2905A uses a TO-39 metal package with case-as-collector configuration, while the 2N2907A uses a TO-18 metal package with isolated collector lead. Physical mounting, thermal path, and pin spacing differ significantly-direct PCB footprint substitution is not possible without layout revision.

What is the maximum continuous collector current at 70°C ambient?

At T_amb = 70 °C, derating begins at 25 °C using R_thj-amb = 250 °C/W. With P_tot = 0.6 W at 25 °C, allowable power drops to 0.45 W at 70 °C. Using V_CE(sat) ≈ −0.4 V at I_C = −150 mA, max continuous I_C remains −0.6 A only if case temperature is actively maintained ≤ 25 °C; otherwise, thermal limits constrain sustained current.

Can the 2N2905A be used in avalanche mode?

No. The 2N2905A is not characterized or rated for controlled avalanche operation. Its absolute maximum V_CEO and V_CBO are −60 V with no specified avalanche energy rating, SOA curves, or ruggedness testing. Use in inductive switching applications requires external clamping (e.g., flyback diode) to prevent destructive breakdown.

Does the TO-39 case require electrical isolation from PCB ground?

Yes. Since the TO-39 metal case is internally connected to the collector terminal, mounting the device to a grounded heatsink or copper pour creates a direct collector-to-ground connection. Isolation washers or insulating pads must be used if collector potential differs from system ground, especially in floating or high-side configurations.

2N2905A Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: TO-205AD, TO-39-3 Metal Can

Packaging:: Bulk

Product Status:: Active

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 600 mA

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 1.6V @ 50mA, 500mA

Current - Collector Cutoff (Max):: 1µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 150mA, 10V

Power - Max:: 800 mW

Frequency - Transition:: -

Operating Temperature:: -65°C ~ 200°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-39 (TO-205AD)

2N2905A FAQ

1.How can I place an order for 2N2905A through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N2905A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for 2N2905A reliable?

The price and inventory of 2N2905A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N2905A is usually 5 days.

3.What payment methods are accepted for 2N2905A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N2905A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N2905A?

2N2905A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N2905A order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for 2N2905A?

For technical support, including 2N2905A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N2905A requirements.

6.How does Aetrix verify that 2N2905A is sourced from the original manufacturer or authorized distributors?

All 2N2905A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 2N2905A meets industry standards.

7.What is the process for return or replacement of 2N2905A?

All 2N2905A units undergo pre-shipment inspection (PSI). If there is an issue with 2N2905A, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The 2N2905A part is unused and in its original packaging.

Return procedure for 2N2905A:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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