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

onsemi BD234G

Name: BD234G
Brand: onsemi
SKU: BD234G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD234G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-225AA, TO-126-3

Datasheet:: BD234G.pdf

Description:: TRANS PNP 45V 2A TO-126

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BD234G from ON Semiconductor is an NPN epitaxial silicon power transistor in TO-126 package, rated for 45 V V_CEO, 2 A continuous collector current, and 25 W collector dissipation at T_C = 25°C. It serves as a medium-power linear amplifier and switching device in DC motor drivers, power supplies, and relay drivers.

For engineers reviewing the BD234G datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO rating, h_FE consistency at 1 A, V_CE(sat) under 0.6 V, thermal derating behavior, and complementary pairing with BD233/BD235/BD237 devices.

Technical Context

The BD234G operates as a general-purpose NPN bipolar junction transistor optimized for linear amplification and hard-switching applications. Its design supports stable DC current gain (h_FE ≥ 40 at I_C = 150 mA, V_CE = 2 V) and low saturation voltage (V_CE(sat) ≤ 0.6 V at I_C = 1 A, I_B = 0.1 A), enabling efficient operation in Class AB audio stages and PWM-controlled loads.

It features a maximum junction temperature of 150°C and safe operating area (SOA) defined up to 10 ms pulse width, with thermal resistance R_θJC consistent with TO-126 mechanical construction. The device is explicitly designated as complementary to BD233/BD235/BD237 - not BD236 or BD238 - per Fairchild/ON Semiconductor documentation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum DC collector-emitter voltage before breakdown; defines upper rail limit in switching circuits.
I_C (DC)	2 A - Continuous collector current capability; sets base drive and heatsink sizing requirements.
P_C (T_C=25°C)	25 W - Maximum power dissipation at case temperature 25°C; requires thermal derating above 25°C.
h_FE	40–25 - DC current gain range at V_CE = 2 V; 40 min at I_C = 150 mA, 25 min at I_C = 1 A; impacts base resistor selection.
V_CE(sat)	≤ 0.6 V - Collector-emitter saturation voltage at I_C = 1 A, I_B = 0.1 A; determines conduction loss and heat generation.
f_T	3 MHz - Current gain bandwidth product at V_CE = 10 V, I_C = 250 mA; limits usable frequency in small-signal amplification.

Pinout & Package

BD234G is housed in a TO-126 plastic package with three leads: Emitter (Lead 1), Collector (Lead 2), Base (Lead 3). The package provides mechanical robustness and moderate thermal performance suitable for medium-power discrete mounting on PCBs with external heatsinking.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit path for majority carriers	Connected to ground or low-side reference; must handle full load current and support emitter degeneration resistors.
2 (Collector)	Current entry path for majority carriers	Connected to load or supply rail; electrically isolated from mounting surface; requires thermal interface to heatsink.
3 (Base)	Control terminal for minority carrier injection	Drives transistor into saturation or cutoff; requires current-limiting resistor to prevent overdrive and thermal runaway.

Key Features

Feature	Design Value
Complementary pairing	Explicitly matched to BD233 (not BD236); enables balanced push-pull output stages with matched V_CEO and h_FE profiles.
Medium-power SOA	Defined pulsed and DC safe operating area up to 10 ms; supports reliable switching of inductive loads like solenoids and relays.
Low V_CE(sat)	≤ 0.6 V at rated I_C/I_B; reduces conduction loss and improves efficiency in linear regulators and motor drivers.
TO-126 thermal interface	Standardized footprint with metal tab for direct heatsink mounting; enables scalable thermal management without custom hardware.

Applications

DC Motor Control	Linear Power Supply Regulator
Use Scenario: Driving 12 V brushed DC motors in industrial actuators with PWM duty cycling up to 5 kHz. IC Role / Device Role / Timing Role: NPN switch controlling motor current path; operated in saturation/cutoff mode with base current limiting. Use Value: V_CE(sat) ≤ 0.6 V minimizes I²R losses at 1–2 A load, reducing thermal stress and eliminating need for oversized heatsinks.	Use Scenario: Pass transistor in adjustable 0–30 V, 1.5 A linear bench power supply with LM317-based control loop. IC Role / Device Role / Timing Role: Series pass element dissipating excess input-output differential voltage; biased in active region. Use Value: h_FE ≥ 40 at 150 mA ensures stable base drive with minimal control circuit overhead and predictable thermal foldback.
Relay Driver Stage	Audio Output Amplifier
Use Scenario: High-current driver for 24 V, 500 mA industrial relays in PLC I/O modules. IC Role / Device Role / Timing Role: Switching transistor interfacing microcontroller GPIO to relay coil; includes flyback diode protection. Use Value: 45 V V_CEO safely clamps inductive kickback spikes up to 40 V, avoiding secondary snubber components.	Use Scenario: Single-ended Class AB output stage in low-fidelity intercom amplifier delivering 2 W into 8 Ω. IC Role / Device Role / Timing Role: Medium-power output transistor biased with fixed emitter resistor; handles peak AC current swing. Use Value: f_T = 3 MHz supports faithful reproduction up to 10 kHz, meeting voice-band fidelity requirements without oscillation.

DC Motor Control

Linear Power Supply Regulator

Use Scenario: Driving 12 V brushed DC motors in industrial actuators with PWM duty cycling up to 5 kHz.

IC Role / Device Role / Timing Role: NPN switch controlling motor current path; operated in saturation/cutoff mode with base current limiting.

Use Value: V_CE(sat) ≤ 0.6 V minimizes I²R losses at 1–2 A load, reducing thermal stress and eliminating need for oversized heatsinks.

Use Scenario: Pass transistor in adjustable 0–30 V, 1.5 A linear bench power supply with LM317-based control loop.

IC Role / Device Role / Timing Role: Series pass element dissipating excess input-output differential voltage; biased in active region.

Use Value: h_FE ≥ 40 at 150 mA ensures stable base drive with minimal control circuit overhead and predictable thermal foldback.

Relay Driver Stage

Audio Output Amplifier

Use Scenario: High-current driver for 24 V, 500 mA industrial relays in PLC I/O modules.

IC Role / Device Role / Timing Role: Switching transistor interfacing microcontroller GPIO to relay coil; includes flyback diode protection.

Use Value: 45 V V_CEO safely clamps inductive kickback spikes up to 40 V, avoiding secondary snubber components.

Use Scenario: Single-ended Class AB output stage in low-fidelity intercom amplifier delivering 2 W into 8 Ω.

IC Role / Device Role / Timing Role: Medium-power output transistor biased with fixed emitter resistor; handles peak AC current swing.

Use Value: f_T = 3 MHz supports faithful reproduction up to 10 kHz, meeting voice-band fidelity requirements without oscillation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN power transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD233G	Same package, same V_CEO (45 V), but lower P_C (15 W) and I_C (1.5 A); h_FE min 40 at 150 mA only.	Suitable for lower-power switching where thermal margin is constrained; not recommended for sustained 2 A loads.	Select BD233G only when power dissipation remains below 12 W and peak I_C ≤ 1.5 A.
MJ15003	Higher V_CEO (120 V), higher P_C (200 W), TO-3 package; h_FE min 20 at 8 A - significantly different gain profile and thermal mass.	Used in high-voltage audio amplifiers and industrial inverters; incompatible pinout and PCB footprint.	Choose MJ15003 only for designs requiring >60 V operation or >50 W dissipation; not a drop-in replacement.

Compared with BD234G, BD233G offers reduced power handling but identical voltage rating and complementary pairing, while MJ15003 delivers far higher voltage and power capability in a physically incompatible TO-3 package - making BD234G the optimal balance of voltage, current, thermal, and layout compatibility for medium-power 45 V systems.

Availability

BD234G is available at Aetrix Electronics and suitable for DC motor control, linear power supply regulation, and relay driver applications requiring stable component supply, long-term industrial availability, and consistent parametric performance across production lots.

Supply support for BD234G 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensor, and logic solutions for automotive, industrial, cloud, and consumer markets.

The BD234G belongs to ON Semiconductor's legacy Fairchild discrete transistor portfolio, designed specifically for cost-sensitive, medium-power linear and switching applications where reliability, thermal stability, and complementary device matching are critical.

FAQ

What is the maximum continuous collector current rating for BD234G?

The BD234G is rated for 2 A continuous collector current (I_C) at case temperature T_C = 25°C. This rating decreases with rising case temperature per the published power derating curve - at 100°C T_C, the usable I_C drops to approximately 1.2 A. Designers must verify thermal design margins using the BD234G's R_θJC and actual board-level thermal resistance.

Is BD234G pin-compatible with BD236G or BD238G?

No - BD234G is explicitly documented as complementary to BD233, BD235, and BD237, not BD236 or BD238. While all share the TO-126 package and pinout (E-C-B), BD236G and BD238G are PNP devices with opposite polarity and different voltage/current ratings. Substituting BD234G for a PNP part will result in circuit failure.

What is the typical V_CE(sat) of BD234G under standard test conditions?

The BD234G exhibits a maximum V_CE(sat) of 0.6 V when tested at I_C = 1 A and I_B = 0.1 A, with V_CE = 2 V. Typical values observed in production lots range from 0.45 V to 0.55 V. This low saturation voltage directly reduces conduction loss and self-heating during switching operation of the BD234G.

Does BD234G have a specified f_T (transition frequency), and what does it imply for circuit use?

Yes - the BD234G has a specified f_T of 3 MHz, measured at V_CE = 10 V and I_C = 250 mA. This indicates the frequency at which current gain drops to unity, limiting its usefulness in RF or high-speed switching. For BD234G, this confirms suitability for audio-frequency amplification and low-kHz PWM switching, but not for >100 kHz SMPS or RF stages.

Can BD234G be used in avalanche mode for inductive load switching?

No - the BD234G is not rated or characterized for controlled avalanche operation. Its absolute maximum V_CEO rating of 45 V applies only under specified test conditions with no repetitive stress. Using BD234G beyond V_CEO risks irreversible breakdown. For inductive loads, always pair BD234G with an external flyback diode or snubber network to clamp voltage transients within its 45 V limit.

BD234G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-225AA, TO-126-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 2 A

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 100mA, 1A

Current - Collector Cutoff (Max):: 100µA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 25 @ 1A, 2V

Power - Max:: 25 W

Frequency - Transition:: 3MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

BD234G FAQ

1.How can I place an order for BD234G through Aetrix?

Please submit a Request for Quotation (RFQ) for BD234G 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 BD234G reliable?

The price and inventory of BD234G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD234G is usually 5 days.

3.What payment methods are accepted for BD234G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD234G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD234G?

BD234G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD234G 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 BD234G?

For technical support, including BD234G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD234G requirements.

6.How does Aetrix verify that BD234G is sourced from the original manufacturer or authorized distributors?

All BD234G 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 BD234G meets industry standards.

7.What is the process for return or replacement of BD234G?

All BD234G units undergo pre-shipment inspection (PSI). If there is an issue with BD234G, 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 BD234G part is unused and in its original packaging.

Return procedure for BD234G:

1.Submit a request within 90 days.

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

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