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

onsemi BD1406STU

Name: BD1406STU
Brand: onsemi
SKU: BD1406STU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD1406STU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BD1406STU.pdf

Description:: TRANS PNP 80V 1.5A TO-126-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BD1406STU from Fairchild Semiconductor is a PNP epitaxial silicon transistor in TO-126 package, rated for -80 V V_CEO, -1.5 A continuous collector current, and 12.5 W case power dissipation at T_C = 25°C, used in medium-power linear amplification and switching applications such as audio output stages and relay drivers.

For engineers reviewing the BD1406STU datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO = -80 V rating, h_FE range of 100–250 at I_C = -150 mA, V_CE(sat) ≤ -0.5 V at I_C = -500 mA/I_B = -50 mA, and TO-126 thermal performance with 1.25 W ambient-rated dissipation.

Technical Context

This PNP bipolar junction transistor operates in active, saturation, and cutoff regions with DC current gain (h_FE) specified across three test conditions: 40–100 at I_C = -5 mA, 63–160 at I_C = -0.5 A, and 100–250 at I_C = -150 mA. Its V_CE(sat) of -0.5 V at forced β = 10 ensures low conduction loss in switching mode.

The device features a maximum junction temperature of 150°C, storage range of -55°C to +150°C, and safe operating area defined up to 100 V and 3 A pulsed (350 µs, 2% duty). Power derating begins at T_C > 25°C at 100 mW/°C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	-80 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines upper rail limit in PNP switch or amplifier stage.
I_C (DC)	-1.5 A - Continuous collector current capability; sets maximum steady-state load drive capacity without thermal runaway.
P_C (T_C=25°C)	12.5 W - Case-mounted power dissipation limit; requires heatsink for sustained operation above ~1.25 W at room ambient.
h_FE (I_C = -150 mA)	100–250 - DC current gain range at mid-current; enables predictable base drive sizing for linear or saturated switching.
V_CE(sat)	≤ -0.5 V @ I_C = -500 mA, I_B = -50 mA - Low saturation voltage reduces power loss and heating in on-state switching applications.
T_J max	150°C - Maximum allowable junction temperature; constrains thermal design margin and heatsink selection.

Pinout & Package

BD1406STU is housed in a TO-126 plastic package with integral metal tab for heatsinking. Pin 1 is Emitter, Pin 2 is Collector (connected to tab), Pin 3 is Base - standard configuration for medium-power PNP transistors in this family.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current source terminal for PNP device	Connected to higher potential rail in common-emitter configuration; carries full load current.
2 (Collector)	Current sink terminal, electrically tied to metal tab	Must be isolated from chassis unless circuit ground is at highest potential; provides primary thermal path to heatsink.
3 (Base)	Control input for minority-carrier injection	Requires negative bias relative to emitter to turn on; base resistor sizing depends on h_FE and desired I_C.

Key Features

Feature	Design Value
High V_CEO rating	-80 V enables use in 48 V and 60 V industrial bus switching without cascading or snubbing.
Medium-power SOA	Defined safe operating area supports 3 A pulsed current at 100 V, suitable for inductive load switching with flyback protection.
TO-126 thermal interface	Metal tab allows direct mounting to heatsink with minimal thermal resistance (R_θJC ≈ 2.5°C/W typical).
h_FE classification	h_FE3 binning (100–250) ensures consistent gain across production lots for reliable base drive design.

Applications

Audio Amplifier Output Stage	Relay Driver Circuit
Use Scenario: Driving 8 Ω speaker loads in Class-B or AB complementary output stages with BD139 NPN counterpart. IC Role / Device Role / Timing Role: PNP output transistor delivering negative half-cycle current; complements BD139 in push-pull topology. Use Value: V_CEO = -80 V and h_FE ≥ 100 ensure headroom and linearity for 20–30 W RMS output without clipping or thermal foldback.	Use Scenario: Switching 24 V DC coils drawing up to 1.2 A in industrial control panels. IC Role / Device Role / Timing Role: Saturated-switch PNP transistor controlling relay coil current with base-driven turn-on/turn-off. Use Value: V_CE(sat) ≤ -0.5 V minimizes coil power loss and self-heating; TO-126 tab enables direct heatsink attachment for 100% duty cycle operation.
DC Motor H-Bridge High-Side	Linear Voltage Regulator Pass Element
Use Scenario: Upper-leg switch in discrete 24 V brushed DC motor H-bridge with freewheeling diode protection. IC Role / Device Role / Timing Role: High-side PNP switch sourcing current to motor winding during forward drive phase. Use Value: 12.5 W case power rating and 150°C T_J allow brief surge currents up to 3 A while maintaining reliability under PWM commutation.	Use Scenario: Series pass element in adjustable 5–15 V, 1 A linear regulator with external error amplifier. IC Role / Device Role / Timing Role: Current-controlled PNP transistor regulating output by dissipating excess input-output differential voltage. Use Value: h_FE stability over I_C and low V_CE(sat) reduce regulation error and improve load transient response.

Audio Amplifier Output Stage

Relay Driver Circuit

Use Scenario: Driving 8 Ω speaker loads in Class-B or AB complementary output stages with BD139 NPN counterpart.

IC Role / Device Role / Timing Role: PNP output transistor delivering negative half-cycle current; complements BD139 in push-pull topology.

Use Value: V_CEO = -80 V and h_FE ≥ 100 ensure headroom and linearity for 20–30 W RMS output without clipping or thermal foldback.

Use Scenario: Switching 24 V DC coils drawing up to 1.2 A in industrial control panels.

IC Role / Device Role / Timing Role: Saturated-switch PNP transistor controlling relay coil current with base-driven turn-on/turn-off.

Use Value: V_CE(sat) ≤ -0.5 V minimizes coil power loss and self-heating; TO-126 tab enables direct heatsink attachment for 100% duty cycle operation.

DC Motor H-Bridge High-Side

Linear Voltage Regulator Pass Element

Use Scenario: Upper-leg switch in discrete 24 V brushed DC motor H-bridge with freewheeling diode protection.

IC Role / Device Role / Timing Role: High-side PNP switch sourcing current to motor winding during forward drive phase.

Use Value: 12.5 W case power rating and 150°C T_J allow brief surge currents up to 3 A while maintaining reliability under PWM commutation.

Use Scenario: Series pass element in adjustable 5–15 V, 1 A linear regulator with external error amplifier.

IC Role / Device Role / Timing Role: Current-controlled PNP transistor regulating output by dissipating excess input-output differential voltage.

Use Value: h_FE stability over I_C and low V_CE(sat) reduce regulation error and improve load transient response.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD127G	V_CEO = -100 V, I_C = -2 A, TO-220 package, higher P_D (30 W), but larger footprint and no integrated tab isolation.	Preferred where higher voltage margin or higher continuous current is required; less suitable for space-constrained TO-126 layouts.	Select MJD127G when system voltage exceeds 80 V or ambient temperature demands >12.5 W dissipation with forced cooling.
BD175	V_CEO = -45 V, I_C = -1.5 A, same TO-126 package, lower voltage rating, h_FE 25–250 (wider spread).	Suitable only for ≤36 V systems; gain variation may require wider base resistor tolerance or feedback compensation.	Choose BD175 only in cost-sensitive 24 V applications where -45 V rating is sufficient and gain consistency is not critical.

Compared with BD1406STU, MJD127G offers higher voltage and power headroom at the cost of board area and thermal interface complexity, while BD175 trades voltage safety margin for footprint compatibility and lower cost in lower-voltage designs.

Availability

BD1406STU is available at Aetrix Electronics and suitable for audio amplifiers, industrial relay drivers, DC motor controllers, and linear voltage regulators requiring stable component supply and long-term obsolescence management.

Supply support for BD1406STU 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 BD1406STU belongs to Fairchild's legacy medium-power PNP transistor product line, designed specifically for robust linear amplification and industrial-grade switching in cost-sensitive, thermally demanding applications.

FAQ

What is the maximum continuous collector current rating for BD1406STU?

The BD1406STU has a maximum continuous collector current (I_C) rating of -1.5 A at T_C = 25°C. This value assumes proper heatsinking; derating applies above 25°C case temperature at 100 mW/°C. At ambient temperature (T_A = 25°C), the usable continuous current drops to -1.25 A due to lower thermal resistance to ambient.

Is BD1406STU pin-compatible with BD139 in complementary pair configurations?

Yes, BD1406STU is the designated PNP complement to the NPN BD139 transistor. Both share identical TO-126 packaging, pinout (Emitter-Collector-Base), and thermal characteristics, enabling direct pairing in Class-B/AB audio output stages and H-bridge circuits without layout modification.

What is the typical V_CE(sat) of BD1406STU under standard switching conditions?

The BD1406STU exhibits a typical V_CE(sat) of -0.5 V when operated at I_C = -500 mA and I_B = -50 mA (forced β = 10). This low saturation voltage is confirmed across production lots and ensures minimal conduction loss in relay driver and motor switch applications.

Does BD1406STU require a heatsink for 1 A continuous operation?

Yes, BD1406STU requires a heatsink for 1 A continuous collector current. At I_C = -1 A and V_CE ≈ -1 V (linear region), power dissipation reaches ~1 W. With R_θJA ≈ 100°C/W (no heatsink), junction temperature would exceed 125°C even at 25°C ambient - exceeding safe operating limits. A minimum 2°C/W heatsink is recommended.

What h_FE bin does BD1406STU fall into according to Fairchild's classification?

BD1406STU corresponds to h_FE3 classification per Fairchild's datasheet, specifying a DC current gain range of 100–250 when measured at V_CE = -2 V and I_C = -150 mA. This bin ensures tighter gain distribution than h_FE1 (25–250) or h_FE2 (25–160), supporting more predictable base drive design.

BD1406STU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: PNP

Current - Collector (Ic) (Max):: 1.5 A

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

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 150mA, 2V

Power - Max:: 1.25 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126-3

BD1406STU FAQ

1.How can I place an order for BD1406STU through Aetrix?

Please submit a Request for Quotation (RFQ) for BD1406STU 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 BD1406STU reliable?

The price and inventory of BD1406STU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD1406STU is usually 5 days.

3.What payment methods are accepted for BD1406STU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD1406STU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD1406STU?

BD1406STU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD1406STU 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 BD1406STU?

For technical support, including BD1406STU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD1406STU requirements.

6.How does Aetrix verify that BD1406STU is sourced from the original manufacturer or authorized distributors?

All BD1406STU 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 BD1406STU meets industry standards.

7.What is the process for return or replacement of BD1406STU?

All BD1406STU units undergo pre-shipment inspection (PSI). If there is an issue with BD1406STU, 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 BD1406STU part is unused and in its original packaging.

Return procedure for BD1406STU:

1.Submit a request within 90 days.

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

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