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

onsemi BD243C

Name: BD243C
Brand: onsemi
SKU: BD243C
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD243C

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BD243C.pdf

Description:: TRANS NPN 100V 6A TO-220-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BD243C from Fairchild Semiconductor is an NPN epitaxial silicon power transistor in TO-220 package, rated for 100 V collector-emitter sustaining voltage (V_CEO(sus)), 6 A DC collector current (I_C), and 65 W collector dissipation at T_C = 25°C. It serves as a medium-power linear amplifier and switching device in motor control, power supply regulation, and audio output stages.

For engineers reviewing the BD243C datasheet, pinout, applications, or equivalent options, key selection criteria include its 100 V V_CEO(sus), 1.5 V V_CE(sat) at I_C = 6 A / I_B = 1 A, h_FE ≥ 15 at I_C = 3 A, TO-220 thermal performance, and complementary pairing with BD244C.

Technical Context

The BD243C operates as a single NPN bipolar junction transistor optimized for medium-power linear and switching applications. Its design supports continuous conduction up to 6 A with forced base drive (I_B ≤ 2 A), exhibits V_BE(on) = 2 V at I_C = 6 A, and maintains safe operation within a 150°C junction temperature limit.

It features a fixed three-terminal configuration (Base–Collector–Emitter) in TO-220 package with electrically isolated collector tab, enabling direct heatsink mounting. The device's V_CEO(sus) = 100 V and I_CP = 10 A (pulsed) define its robustness in inductive load switching and regulated DC-DC stage designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO(sus)	100 V - Sustaining voltage under open-base condition; defines maximum safe blocking capability in switching mode
I_C (DC)	6 A - Continuous collector current rating; sets upper bound for steady-state power delivery
P_C @ T_C=25°C	65 W - Maximum power dissipation with case held at 25°C; requires heatsinking for practical use
V_CE(sat)	1.5 V @ I_C=6 A, I_B=1 A - Low saturation voltage enables efficient switching with <10 W conduction loss
h_FE	≥15 @ I_C=3 A - Minimum DC current gain ensures reliable base drive sizing for 6 A loads
T_J max	150°C - Absolute junction temperature limit; constrains thermal design margin in enclosed environments
V_EBO	5 V - Emitter-base reverse breakdown voltage; limits negative bias tolerance during turn-off transients

Pinout & Package

BD243C uses the standard TO-220 package with electrically isolated collector tab (pin 2), non-isolated plastic body, and 3-pin straight lead configuration. Mounting hole allows mechanical fixation and thermal coupling to heatsink.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal requiring ~1 A drive current to saturate 6 A collector current; low-impedance input for BJT switching
2	Collector	Main high-current output terminal; electrically isolated metal tab enables direct heatsink attachment without insulator
3	Emitter	Common return path for collector and base currents; tied to system ground or low-side switch reference

Key Features

Feature	Design Value
High V_CEO(sus)	100 V rating enables use in 48 V industrial bus and 100 V flyback snubber circuits without derating
Low V_CE(sat)	1.5 V saturation voltage minimizes conduction losses in 6 A switching applications (e.g., solenoid drivers)
TO-220 thermal interface	Isolated collector tab supports >30 W dissipation with standard 1°C/W heatsink, reducing need for complex thermal layout
Complementary pairing	Designed as NPN counterpart to BD244C PNP, enabling push-pull output stages with matched voltage ratings
Robust pulse handling	10 A pulsed collector current (I_CP) supports short-duration inrush current management in relay and lamp drivers

Applications

Motor Drive Stage	Linear Regulator Pass Element
Use Scenario: Driving 24–48 V DC brushed motors in industrial actuators with PWM switching at ≤20 kHz. IC Role / Device Role / Timing Role: NPN power switch controlling motor current path; base driven by microcontroller GPIO via resistor network. Use Value: 100 V V_CEO(sus) prevents breakdown during inductive kickback; 65 W dissipation accommodates 5 A continuous stall current with heatsink.	Use Scenario: Series pass transistor in adjustable 3–30 V, 3 A linear regulator for analog sensor power supplies. IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output by dissipating excess input-output differential voltage. Use Value: 6 A I_C rating provides headroom above 3 A load; 1.5 V V_CE(sat) reduces dropout and improves efficiency at full load.
Audio Output Amplifier	Power Supply Switching Transistor
Use Scenario: Complementary emitter-follower output stage in 10 W Class AB audio amplifiers operating from ±24 V rails. IC Role / Device Role / Timing Role: NPN half of push-pull pair delivering current to speaker load; biased in linear region for low-distortion operation. Use Value: h_FE ≥ 15 at 3 A ensures stable bias point across temperature; TO-220 package enables compact heatsink integration near output transformer.	Use Scenario: Main switching transistor in 12 V input, 5 V/6 A buck converter with synchronous rectification. IC Role / Device Role / Timing Role: High-side or low-side switch cycling at 100–500 kHz; conducts during on-time, blocks during off-time. Use Value: 100 V V_CEO(sus) tolerates 2× input voltage spikes; 10 A I_CP handles startup surge without secondary overcurrent protection.

Motor Drive Stage

Linear Regulator Pass Element

Use Scenario: Driving 24–48 V DC brushed motors in industrial actuators with PWM switching at ≤20 kHz.

IC Role / Device Role / Timing Role: NPN power switch controlling motor current path; base driven by microcontroller GPIO via resistor network.

Use Value: 100 V V_CEO(sus) prevents breakdown during inductive kickback; 65 W dissipation accommodates 5 A continuous stall current with heatsink.

Use Scenario: Series pass transistor in adjustable 3–30 V, 3 A linear regulator for analog sensor power supplies.

IC Role / Device Role / Timing Role: Voltage-controlled current source regulating output by dissipating excess input-output differential voltage.

Use Value: 6 A I_C rating provides headroom above 3 A load; 1.5 V V_CE(sat) reduces dropout and improves efficiency at full load.

Audio Output Amplifier

Power Supply Switching Transistor

Use Scenario: Complementary emitter-follower output stage in 10 W Class AB audio amplifiers operating from ±24 V rails.

IC Role / Device Role / Timing Role: NPN half of push-pull pair delivering current to speaker load; biased in linear region for low-distortion operation.

Use Value: h_FE ≥ 15 at 3 A ensures stable bias point across temperature; TO-220 package enables compact heatsink integration near output transformer.

Use Scenario: Main switching transistor in 12 V input, 5 V/6 A buck converter with synchronous rectification.

IC Role / Device Role / Timing Role: High-side or low-side switch cycling at 100–500 kHz; conducts during on-time, blocks during off-time.

Use Value: 100 V V_CEO(sus) tolerates 2× input voltage spikes; 10 A I_CP handles startup surge without secondary overcurrent protection.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD243G	Same V_CEO(sus) = 100 V, but in DPAK package; lower P_C = 35 W; h_FE min = 30 @ I_C = 3 A	Suitable for surface-mount PCBs with limited heatsinking; not interchangeable in through-hole TO-220 footprints	Select MJD243G only when SMT assembly and reduced thermal mass are required; verify PCB pad thermal relief matches DPAK specs.
BD243CTU	Identical electrical specs and TO-220 package; differs only in tape-and-reel packaging and RoHS compliance marking	No functional difference; intended for automated pick-and-place vs. loose part distribution	BD243CTU is drop-in compatible for volume production; choose based on assembly line requirements, not circuit design.

Compared with MJD243G and BD243CTU, the BD243C offers higher power dissipation (65 W vs. 35 W) in through-hole format, while BD243CTU provides identical performance in RoHS-compliant tape-and-reel form-making BD243C optimal for manual prototyping and high-power thermal designs.

Availability

BD243C is available at Aetrix Electronics and suitable for motor control, linear regulator, and audio amplifier applications requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for BD243C 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The BD243C belongs to Fairchild's legacy medium-power bipolar transistor family, designed specifically for cost-sensitive industrial and consumer linear/switching applications where robustness, thermal reliability, and complementary PNP pairing were essential.

FAQ

What is the maximum continuous collector current rating for BD243C?

The BD243C has a maximum DC collector current (I_C) rating of 6 A at case temperature T_C = 25°C. This rating assumes adequate heatsinking; actual usable current decreases with rising case temperature per the power derating curve in the datasheet. At T_C = 100°C, the allowable I_C drops to approximately 3.2 A. The BD243C must be mounted on a heatsink to sustain this current continuously.

Does BD243C have a built-in base-emitter resistor or protection diode?

No, the BD243C is a standard three-terminal NPN bipolar junction transistor with no integrated base-emitter resistor or protection diode. External base resistors must be used to limit base current, and external clamping diodes (e.g., flyback diodes) are required for inductive load switching. This discrete architecture gives designers full control over drive conditions but requires careful external component selection.

Can BD243C replace BD243B in an existing design?

Yes, BD243C can replace BD243B because it meets or exceeds all BD243B specifications: V_CEO(sus) = 100 V (vs. 80 V), same I_C = 6 A, identical package and pinout. However, verify that the higher voltage rating does not introduce unintended stress on associated components (e.g., base drive circuitry or snubbers). The BD243C remains fully compatible in footprint and function.

What is the typical V_CE(sat) of BD243C under full-load conditions?

The BD243C exhibits a typical collector-emitter saturation voltage (V_CE(sat)) of 1.5 V when operated at I_C = 6 A and I_B = 1 A. This value is confirmed under pulsed test conditions (PW = 300 µs, duty cycle <20%). Under continuous DC operation with proper heatsinking, V_CE(sat) remains within ±0.2 V of this value, directly impacting conduction loss and thermal design.

Is BD243C suitable for automotive applications?

The BD243C is not AEC-Q101 qualified and lacks automotive-grade screening, temperature range extension beyond –65°C to +150°C, or enhanced transient immunity. While it may function in non-safety-critical 12 V automotive auxiliary circuits (e.g., fan control), Fairchild did not specify it for automotive use. For production automotive systems, AEC-Q101-compliant alternatives like MJD243G or NSS12601CF8 should be selected instead of BD243C.

BD243C Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 6 A

Voltage - Collector Emitter Breakdown (Max):: 100 V

Vce Saturation (Max) @ Ib, Ic:: 1.5V @ 1A, 6A

Current - Collector Cutoff (Max):: 700µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 15 @ 3A, 4V

Power - Max:: 65 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220-3

BD243C FAQ

1.How can I place an order for BD243C through Aetrix?

Please submit a Request for Quotation (RFQ) for BD243C 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 BD243C reliable?

The price and inventory of BD243C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD243C is usually 5 days.

3.What payment methods are accepted for BD243C?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD243C transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD243C?

BD243C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD243C 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 BD243C?

For technical support, including BD243C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD243C requirements.

6.How does Aetrix verify that BD243C is sourced from the original manufacturer or authorized distributors?

All BD243C 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 BD243C meets industry standards.

7.What is the process for return or replacement of BD243C?

All BD243C units undergo pre-shipment inspection (PSI). If there is an issue with BD243C, 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 BD243C part is unused and in its original packaging.

Return procedure for BD243C:

1.Submit a request within 90 days.

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

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