Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

STMicroelectronics BD243C

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

Compare

Part No.:: BD243C

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BD243C.pdf

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

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:7,299

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BD243C from STMicroelectronics is a silicon NPN epitaxial-base power transistor in TO-220 package, rated for 100 V V_CEO, 6 A continuous collector current, and 65 W total dissipation at T_c ≤ 25 °C. It serves as a medium-power linear amplifier and switching device in DC motor drives, power supplies, and audio output stages.

For engineers reviewing the BD243C datasheet, BD243C pinout, BD243C application, or BD243C equivalent, key selection criteria include V_CEO = 100 V, I_C = 6 A, h_FE ≥ 15 at 3 A, R_thj-case = 1.92 °C/W, and safe operating area compliance for pulsed switching.

Technical Context

The BD243C operates as a general-purpose bipolar junction transistor with fixed-base drive architecture and inherent thermal limitations governed by its TO-220 package's junction-to-case thermal resistance of 1.92 °C/W. Its DC current gain (h_FE) ranges from 30 at 0.3 A to 15 at 3 A under V_CE = 4 V, supporting both linear biasing and saturated switching.

It features a pulsed V_CEO(sus) rating of 100 V at I_C = 30 mA, V_CE(sat) ≤ 1.5 V at I_C = 6 A/I_B = 1 A, and V_BE ≈ 2 V under same conditions-enabling predictable base drive sizing and thermal margin estimation in discrete power stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - Maximum sustainable collector-emitter voltage with base open; defines upper rail limit in switching applications.
I_C	6 A - Continuous DC collector current; sets maximum load-handling capability without forced cooling.
P_tot	65 W - Total power dissipation at case temperature ≤25 °C; requires heatsink for sustained operation above ~10 W.
h_FE	15 (min) at I_C = 3 A - Minimum DC current gain used to size base drive resistor for saturation in switch mode.
R_thj-case	1.92 °C/W - Junction-to-case thermal resistance; determines temperature rise per watt dissipated across the die-to-heatsink interface.
V_CE(sat)	≤1.5 V at I_C = 6 A, I_B = 1 A - Saturation voltage defining conduction loss and heat generation during on-state.

Pinout & Package

BD243C is housed in a standard JEDEC TO-220 plastic package with three leads: emitter (pin 1), base (pin 2), collector (pin 3). The metal tab is electrically connected to the collector and must be insulated if mounted to a grounded heatsink.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current exit path for majority carriers	Reference node for base bias network; common return for load current in low-side switch configuration.
2 (Base)	Control terminal for minority carrier injection	Receives current-limited drive signal; requires ≥1 A for full saturation at 6 A collector current.
3 (Collector)	Current entry path and thermal interface	Connected to high-side rail or inductive load; metal tab conducts heat and must be electrically isolated from chassis ground.

Key Features

Feature	Design Value
High V_CEO rating	100 V enables use in 48 V industrial bus systems and offline auxiliary supplies without derating.
Low V_CE(sat)	≤1.5 V at full rated current minimizes conduction loss and simplifies thermal design in linear regulators.
Robust SOA	Defined safe operating area supports pulsed inductive loads up to 100 V × 6 A with 2% duty cycle.
TO-220 mechanical standardization	Compatible with widely available heatsinks and mounting hardware across industrial power designs.

Applications

DC Motor Control

Linear Power Supply

Use Scenario: Bidirectional 24–48 V brushed DC motor driver using complementary pair with BD244C.

IC Role / Device Role / Timing Role: NPN power switch in H-bridge low-side leg, handling peak currents up to 6 A.

Use Value: 100 V V_CEO provides margin against back-EMF spikes; 1.5 V V_CE(sat) limits power loss to <10 W at full load.

Use Scenario: Series pass transistor in adjustable 0–30 V, 3 A bench power supply.

IC Role / Device Role / Timing Role: Linear regulator pass element dissipating up to 45 W under worst-case dropout.

Use Value: 65 W P_tot and 1.92 °C/W R_thj-case allow stable operation with moderate heatsinking at full output.

Audio Amplifier Output

Relay/Solenoid Driver

Use Scenario: Complementary Class-AB output stage in 20 W mono audio amplifier.

IC Role / Device Role / Timing Role: Medium-power NPN emitter-follower delivering current to 4–8 Ω speaker load.

Use Value: h_FE ≥15 at 3 A ensures stable bias current control; low V_CE(sat) preserves output swing near rails.

Use Scenario: High-current solenoid actuator driver in industrial valve control module.

IC Role / Device Role / Timing Role: Single-ended switch driving 12–24 V, 5 A inductive load with flyback protection.

Use Value: 100 V V_CEO withstands >60 V flyback transients; 10 A I_CM accommodates startup surge.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TIP31C	V_CEO = 100 V, I_C = 3 A, P_tot = 40 W - lower current and power rating.	Not suitable for 6 A continuous loads; limited to ≤2 A average current in switching use.	Select when thermal budget is tight and peak current ≤3 A; verify SOA for inductive turn-off.
MJE13009	V_CEO = 400 V, I_C = 12 A, P_tot = 100 W - higher voltage/current but slower switching.	Over-specified for 100 V systems; introduces unnecessary gate drive complexity in linear use.	Prefer only where 400 V breakdown or >6 A surge tolerance is mandatory; otherwise increases cost and footprint.

Compared with TIP31C and MJE13009, BD243C offers optimal balance of 100 V rating, 6 A capacity, and TO-220 thermal performance for medium-power linear and switching tasks-neither under-specified nor over-engineered for 24–48 V industrial loads.

Availability

BD243C is available at Aetrix Electronics and suitable for DC motor control, linear power supplies, audio amplifier outputs, and relay/solenoid drivers requiring stable component supply and long-term industrial availability.

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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs and discrete devices for automotive, industrial, and consumer markets.

The BD243C belongs to ST's legacy power bipolar transistor family, developed specifically for robust, cost-effective medium-power linear amplification and switching in industrial equipment and power conversion systems.

FAQ

Is BD243C pin-compatible with BD243B?

Yes, BD243C is pin-compatible with BD243B and shares identical TO-220 pinout (E-B-C), but offers higher V_CEO (100 V vs. 80 V) and V_CEO(sus) ratings. No PCB redesign is needed when upgrading from BD243B to BD243C in existing layouts.

What is the maximum safe continuous collector current at 70 °C case temperature?

At T_c = 70 °C, derating begins at 0.5 W/°C beyond 25 °C. With 65 W max at 25 °C, allowable dissipation drops to 42.5 W. Using V_CE(sat) ≈ 1.5 V, maximum continuous I_C is approximately 28.3 A - but I_C rating remains 6 A due to bond wire and packaging limits, not thermal alone.

Does BD243C require a base resistor in switching applications?

Yes - BD243C requires an external base current-limiting resistor to deliver ≥1 A base current for full saturation at 6 A collector current. Typical value is 10–22 Ω when driven from 12–15 V logic, accounting for V_BE ≈ 2 V and driver capability.

Can BD243C be used in parallel for higher current?

No - BD243C lacks built-in emitter ballasting resistors and exhibits positive thermal feedback. Parallel operation without individual emitter resistors risks current hogging and thermal runaway. Use a single higher-rated device (e.g., BD245C) instead.

BD243C Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

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

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.

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…