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

STMicroelectronics BDX53B

Name: BDX53B
Brand: STMicroelectronics
SKU: BDX53B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BDX53B

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: BDX53B.pdf

Description:: TRANS NPN DARL 80V 8A TO-220

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BDX53B from STMicroelectronics is an NPN complementary power Darlington transistor in TO-220 package, featuring 80 V V_CEO, 8 A I_C, 60 W P_TOT, integrated antiparallel collector-emitter diode, and monolithic planar construction with base island layout - used in high-current linear audio output stages and industrial switching regulators.

For engineers reviewing the BDX53B datasheet, BDX53B pinout, BDX53B application, or BDX53B equivalent, key selection criteria include V_CEO(sus) = 80 V, h_FE ≥ 750 at 3 A, V_CE(sat) ≤ 2 V, thermal resistance R_thJC = 2.08 °C/W, and integrated clamping diode functionality for inductive load protection.

Technical Context

The BDX53B implements a monolithic Darlington pair with built-in antiparallel diode across C–E terminals, enabling safe commutation of inductive loads without external flyback components. Its planar "base island" layout ensures stable h_FE linearity and high f_T performance under sustained current stress.

Designed for linear and switching operation up to 150 °C junction temperature, it supports DC biasing with 0.2 A max base current and delivers 750× DC current gain at 3 A collector current and 3 V V_CE, with saturation voltage specified at ≤2 V under same conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	80 V - maximum safe collector-emitter blocking voltage in linear mode
I_C	8 A continuous - supports high-power audio output and motor drive stages
P_TOT	60 W at T_C = 25 °C - requires heatsink for sustained >10 W dissipation
h_FE	≥750 at I_C = 3 A - enables low-base-drive control in high-gain amplifier designs
R_thJC	2.08 °C/W - defines thermal path efficiency from junction to case mounting surface
V_F	1.8–2.5 V at I_F = 3–8 A - integrated diode provides bidirectional current path for inductive kickback
V_CE(sat)	≤2 V at I_C = 3 A, I_B = 12 mA - limits conduction loss in switching applications

Pinout & Package

BDX53B uses TO-220 type A package with metal tab (collector) mounted to heatsink. Pin 1 = Base, Pin 2 = Collector (tab), Pin 3 = Emitter. Internal resistors R1 ≈ 10 kΩ and R2 ≈ 150 Ω provide base bias stabilization and current limiting.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Base)	Control input	Receives base drive current (max 0.2 A); connected internally to R1 (10 kΩ) and R2 (150 Ω)
Pin 2 (Collector / Tab)	Main current path input & thermal interface	Electrically and thermally connected to metal tab; must be electrically isolated from heatsink unless circuit design permits common-collector configuration
Pin 3 (Emitter)	Current return path	Output terminal for emitter-follower or common-collector configurations; referenced to system ground in most linear amplifier topologies

Key Features

Feature	Design Value
Monolithic Darlington pair	Single-die integration eliminates inter-device matching drift and improves thermal coupling for consistent h_FE behavior
Integrated antiparallel C–E diode	Eliminates need for external flyback diode in relay/motor driver circuits, reducing BOM count and PCB area
Base island planar layout	Enhances current handling uniformity and reduces localized hot spots during high-current pulses
h_FE linearity	Supports low-distortion Class AB audio amplification without dynamic gain compression at full output swing
High f_T	Enables stable operation up to mid-audio frequencies (≥1 MHz typical) with minimal phase shift in feedback loops

Applications

Audio Power Amplifiers

Industrial DC Motor Drivers

Use Scenario: Output stage in 20–50 W discrete Class AB audio amplifiers driving 4–8 Ω speakers.

IC Role / Device Role / Timing Role: NPN Darlington emitter-follower delivering high current swing with low V_CE(sat) and minimal crossover distortion.

Use Value: 750× h_FE reduces required driver stage gain; integrated diode prevents speaker coil back-EMF damage during transient clipping.

Use Scenario: H-bridge half-bridge switch controlling 24–48 V brushed DC motors in PLC-controlled factory equipment.

IC Role / Device Role / Timing Role: High-current switching element with fast turn-off aided by internal base resistor network and clamping diode recovery path.

Use Value: 8 A I_C and 80 V V_CEO support 40 V nominal bus with 20 % overvoltage margin; R_thJC = 2.08 °C/W enables compact heatsinking.

Linear Voltage Regulators

Switch-Mode Power Supply Pass Elements

Use Scenario: Series pass transistor in adjustable 3–30 V, 3 A linear regulators for test equipment power supplies.

IC Role / Device Role / Timing Role: High-gain series regulator element operating in active region with precise V_BE tracking and thermal stability.

Use Value: Good h_FE linearity ensures stable loop gain across load range; 150 °C T_J(max) allows operation under sustained thermal stress.

Use Scenario: Synchronous rectifier or auxiliary pass transistor in 100–500 kHz SMPS secondary-side regulation.

IC Role / Device Role / Timing Role: Low-saturation switch managing peak currents during duty-cycle transitions with controlled di/dt via integrated diode.

Use Value: V_F ≤ 2.5 V at 8 A minimizes reverse-recovery losses; monolithic structure avoids mismatch-induced shoot-through risk.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127	TO-252 (DPAK), lower P_TOT = 30 W, V_CEO = 80 V, h_FE = 1000–2000 at 1 A	Suitable for surface-mount, medium-power designs where thermal mass and heatsink area are constrained	Select when board space is limited and peak power < 25 W; verify R_thJA derating for ambient > 60 °C
TIP142	TO-220, same V_CEO = 100 V, higher I_C = 10 A, no integrated diode, h_FE = 1000 min at 5 A	Requires external flyback diode but offers higher current headroom and tighter h_FE binning	Select when designing for >8 A peak loads or when discrete diode placement improves layout symmetry and EMI control

Compared with MJD127 and TIP142, BDX53B uniquely combines TO-220 mechanical robustness, integrated clamping diode, and proven h_FE linearity at 3–8 A - making it optimal for legacy audio amplifier replacements and industrial analog control systems requiring field-proven reliability.

Availability

BDX53B is available at Aetrix Electronics and suitable for audio power amplifiers, industrial DC motor drivers, linear voltage regulators, and switch-mode power supply pass elements requiring stable component supply and long-lifecycle support.

Supply support for BDX53B 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, designing and manufacturing microcontrollers, power transistors, sensors, and analog ICs for industrial, automotive, and consumer markets.

BDX53B belongs to ST's legacy power bipolar transistor family, engineered specifically for high-fidelity linear amplification and rugged industrial switching - emphasizing thermal stability, gain consistency, and integrated protection features.

FAQ

Is BDX53B pin-compatible with BDX53C?

No. While both share identical TO-220 pinout (Base–Collector–Emitter), BDX53C has higher V_CEO = 100 V and different internal resistor values (R1/R2 tolerances vary per revision). Substitution requires verification of voltage margin and base drive compatibility in the target circuit.

Can BDX53B replace TIP122 in existing designs?

Yes, with caution: both are NPN Darlington TO-220 transistors, but BDX53B has higher P_TOT (60 W vs. 50 W), lower V_CE(sat) (≤2 V vs. ≤3 V), and integrated diode. Verify that base drive current (12 mA vs. 10 mA) and thermal interface requirements match the original layout.

What is the function of the internal R1 and R2 resistors?

R1 (≈10 kΩ) connects base to collector for self-bias stabilization; R2 (≈150 Ω) is a base-emitter shunt resistor that improves turn-off speed and prevents latch-up during high dv/dt transients. These are monolithically integrated and not user-accessible.

Does BDX53B require a heatsink in all applications?

Yes - even at 1 W dissipation, junction temperature rise exceeds safe limits without thermal management. With R_thJC = 2.08 °C/W and max T_J = 150 °C, a heatsink with R_thSA ≤ 10 °C/W is required for sustained operation above ~5 W at 25 °C ambient.

BDX53B Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Active

Transistor Type:: NPN - Darlington

Current - Collector (Ic) (Max):: 8 A

Voltage - Collector Emitter Breakdown (Max):: 80 V

Vce Saturation (Max) @ Ib, Ic:: 2V @ 12mA, 3A

Current - Collector Cutoff (Max):: 500µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 750 @ 3A, 3V

Power - Max:: 60 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

BDX53B FAQ

1.How can I place an order for BDX53B through Aetrix?

Please submit a Request for Quotation (RFQ) for BDX53B 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 BDX53B reliable?

The price and inventory of BDX53B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BDX53B is usually 5 days.

3.What payment methods are accepted for BDX53B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BDX53B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BDX53B?

BDX53B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BDX53B 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 BDX53B?

For technical support, including BDX53B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BDX53B requirements.

6.How does Aetrix verify that BDX53B is sourced from the original manufacturer or authorized distributors?

All BDX53B 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 BDX53B meets industry standards.

7.What is the process for return or replacement of BDX53B?

All BDX53B units undergo pre-shipment inspection (PSI). If there is an issue with BDX53B, 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 BDX53B part is unused and in its original packaging.

Return procedure for BDX53B:

1.Submit a request within 90 days.

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

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