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

onsemi BD442

Name: BD442
Brand: onsemi
SKU: BD442
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD442

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BD442.pdf

Description:: TRANS PNP 80V 4A TO-126

Quantity:: RFQ Add To RFQ list

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Inventory:2,041

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Product details

Overview

BD442 from STMicroelectronics is a PNP silicon power transistor in SOT-32 (TO-126) package, rated for -80 V V_CEO, -4 A I_C, and 36 W P_TOT at T_case = 25 °C. It delivers high DC current gain (h_FE up to 140 at I_C = -2 A) and low saturation voltage (V_CE(sat) = -0.8 V @ I_C = -2 A, I_B = -0.2 A), enabling efficient linear regulation and industrial switching in motor drivers and power supplies.

For engineers reviewing the BD442 datasheet, BD442 pinout, BD442 application, or BD442 equivalent, key selection criteria include verified PNP polarity, TO-126 mechanical compatibility, guaranteed V_CEO ≥ -80 V, h_FE ≥ 15 at I_C = -10 mA, and thermal performance validated at T_J = 150 °C.

Technical Context

The BD442 uses Planar "Base Island" layout to achieve high h_FE stability across collector current range (-10 mA to -2 A) and low V_CE(sat) under heavy conduction. Its rugged construction supports pulsed I_CM = -7 A (t_p < 10 ms) and sustained operation at T_J = 150 °C.

Designed for non-inductive resistive load switching, it exhibits documented turn-on/off times under standardized test conditions (Figure 7), with V_BE = -1.5 V at I_C = -2 A, confirming strong base drive capability for fast saturation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-80 V - Ensures safe operation in 48 V industrial bus systems with margin against transients.
I_C	-4 A continuous - Supports medium-power load control without forced cooling in TO-126 package.
P_TOT	36 W at T_case = 25 °C - Enables >20 W dissipation with standard heatsink mounting.
h_FE	140 max @ I_C = -2 A - Reduces required base drive current in high-current switching stages.
V_CE(sat)	-0.8 V @ I_C = -2 A, I_B = -0.2 A - Limits conduction loss to ≤1.6 W at full rated current.
T_J max	150 °C - Permits operation in enclosed industrial enclosures without derating below ambient 85 °C.

Pinout & Package

SOT-32 (TO-126) package: 3-pin through-hole, epoxy molded, with emitter (pin 1), base (pin 2), and collector (pin 3) terminals. Collector tab is internally connected to pin 3 and serves as primary heat path.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Emitter)	Current exit terminal for PNP device	Connected to positive rail in high-side switch configurations; requires low-impedance return path.
Pin 2 (Base)	Control input for minority-carrier injection	Accepts negative bias relative to emitter; drives with -0.2 A enables full saturation at -2 A collector current.
Pin 3 (Collector)	Main current sink terminal	Internally bonded to metal tab; must be electrically isolated and thermally coupled to heatsink.

Key Features

Feature	Design Value
High h_FE at high I_C	h_FE ≥ 130 @ I_C = -500 mA - Reduces base driver complexity in relay and solenoid interfaces.
Low V_CE(sat)	-0.8 V @ I_C = -2 A - Minimizes power loss and self-heating during continuous conduction.
Rugged pulsed rating	I_CM = -7 A (t_p < 10 ms) - Handles inrush currents in motor start-up and capacitor charging circuits.
ECOPACK® compliance	Lead-free second-level interconnect - Meets RoHS and JEDEC JESD97 requirements for industrial manufacturing.

Applications

Industrial Linear Regulators

DC Motor Drivers

Use Scenario: High-current series pass element in adjustable 0–30 V, 3 A bench power supplies.

IC Role / Device Role / Timing Role: PNP pass transistor controlling output voltage via feedback loop; operates in active region with constant base bias.

Use Value: Low V_CE(sat) and stable h_FE ensure <1% load regulation error and minimal thermal drift over 0–40 °C ambient.

Use Scenario: High-side switch for bidirectional 24 V brushed DC motors in PLC-controlled conveyors.

IC Role / Device Role / Timing Role: PNP switching transistor driven by optocoupled logic; handles stall current up to -4 A.

Use Value: Verified V_CEO = -80 V withstands back-EMF spikes; pulsed I_CM rating absorbs startup surges without failure.

Relay/Solenoid Drivers

Power Supply OR-ing Circuits

Use Scenario: Driving 24 V/500 mA industrial relays in safety-critical control panels.

IC Role / Device Role / Timing Role: Saturated PNP switch turning on relay coil; base driven by microcontroller GPIO via current-limiting resistor.

Use Value: h_FE ≥ 40 @ I_C = -500 mA ensures reliable saturation with ≤12 mA base current, reducing MCU loading.

Use Scenario: Reverse-polarity protection and OR-ing diode replacement in dual 12 V redundant power inputs.

IC Role / Device Role / Timing Role: PNP configured as low-loss series pass element; emitter tied to input, collector to output, base biased to control conduction.

Use Value: V_CE(sat) = -0.8 V cuts forward drop by >1.2 V vs. Schottky diode, reducing heat generation by >60% at 3 A.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD441	NPN complement; identical package, same V_CEO/I_C/P_TOT, but opposite polarity	Requires inverted drive logic and low-side switching topology	Select when circuit architecture mandates NPN configuration or complementary pair usage.
MJD44H11	Higher V_CEO (-100 V), same I_C (-4 A), TO-252 (DPAK) surface-mount package	Not pin-compatible; requires PCB redesign; better suited for automated assembly	Choose for higher transient immunity or SMT production, accepting layout change and thermal interface adjustment.

Compared with BD441 and MJD44H11, the BD442 provides optimal fit for through-hole, high-gain, high-voltage PNP switching where base drive efficiency and thermal management in TO-126 are prioritized over polarity flexibility or SMT compatibility.

Availability

BD442 is available at Aetrix Electronics and suitable for industrial linear regulators, DC motor drivers, relay/solenoid interfaces, and redundant power supply OR-ing circuits requiring stable component supply and long-term manufacturability.

Supply support for BD442 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 analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The BD442 belongs to ST's legacy bipolar power transistor family, engineered specifically for robust, cost-effective linear and switching power control in industrial equipment where reliability under sustained thermal stress is critical.

FAQ

What is the maximum safe operating temperature for BD442?

The BD442 has a maximum junction temperature (T_J) of 150 °C and a storage temperature range of -65 to 150 °C. For continuous operation, case temperature must remain ≤25 °C to maintain full 36 W power dissipation; derating is required above that point per the datasheet thermal curve. Heatsinking is mandatory above ~10 W dissipation.

Is BD442 pin-compatible with BD439 or BD441?

No. BD442 (SOT-32/TO-126, PNP) is not pin-compatible with BD439 (SOT-32, PNP but different internal layout and gain profile) or BD441 (same package but NPN). Pin 1 is emitter for BD442, while BD441 has emitter on pin 3. Swapping them causes immediate circuit failure due to reversed polarity and incorrect terminal assignment.

Can BD442 replace a TIP42C in existing designs?

Yes, with verification. Both are PNP TO-126 transistors rated for -100 V (TIP42C) vs. -80 V (BD442), so voltage margin is reduced. BD442 offers higher h_FE (140 vs. 30–75) and lower V_CE(sat) (-0.8 V vs. -1.5 V), improving efficiency-but design review must confirm -80 V suffices for the application's worst-case transients.

Does BD442 require a base resistor in switching applications?

Yes. A current-limiting base resistor is mandatory to prevent excessive I_B and thermal runaway. For I_C = -2 A saturation, I_B ≈ -0.2 A is required; with V_BE ≈ -1.5 V and 5 V logic drive, a 17 Ω ±5% resistor ensures correct bias. Layout must minimize base lead inductance to avoid oscillation during switching.

BD442 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):: 4 A

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

Vce Saturation (Max) @ Ib, Ic:: 800mV @ 300mA, 3A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 500mA, 1V

Power - Max:: 36 W

Frequency - Transition:: 3MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

BD442 FAQ

1.How can I place an order for BD442 through Aetrix?

Please submit a Request for Quotation (RFQ) for BD442 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 BD442 reliable?

The price and inventory of BD442 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD442 is usually 5 days.

3.What payment methods are accepted for BD442?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD442 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD442?

BD442 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD442 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 BD442?

For technical support, including BD442 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD442 requirements.

6.How does Aetrix verify that BD442 is sourced from the original manufacturer or authorized distributors?

All BD442 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 BD442 meets industry standards.

7.What is the process for return or replacement of BD442?

All BD442 units undergo pre-shipment inspection (PSI). If there is an issue with BD442, 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 BD442 part is unused and in its original packaging.

Return procedure for BD442:

1.Submit a request within 90 days.

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

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