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

onsemi BD135

Name: BD135
Brand: onsemi
SKU: BD135
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BD135

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BD135.pdf

Description:: TRANS NPN 45V 1.5A TO-126

Quantity:: RFQ Add To RFQ list

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Inventory:6,996

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Product details

Overview

BD135 from onsemi is a plastic medium-power silicon NPN transistor designed for audio amplifier and driver stages in complementary or quasi-complementary circuits. It features 45 V_CEO, 1.5 A collector current, 12.5 W power dissipation at T_C = 25°C, and DC current gain (h_FE) of 25–250 at I_C = 5 mA to 500 mA. It is used in low-to-medium power linear audio output stages.

For engineers reviewing the BD135 datasheet, pinout, applications, or equivalent options, key selection considerations include V_CEO/V_CBO ratings, thermal resistance (R_JC = 10°C/W), saturation voltage (V_CE(sat) ≤ 0.5 V at I_C = 0.5 A), h_FE range, and TO-225 package compatibility with heatsink mounting.

Technical Context

The BD135 operates as a linear NPN bipolar junction transistor with fixed-emitter biasing capability in Class-A or Class-AB audio output configurations. Its 45 V_CEO rating supports operation in ±20 V rail systems, while its 12.5 W T_C-referenced dissipation enables direct heatsink mounting without forced air.

It exhibits h_FE ≥ 25 at I_C = 5 mA and ≥ 40 at I_C = 150 mA, supporting stable biasing across signal swing. V_BE(on) ≤ 1.0 V and V_CE(sat) ≤ 0.5 V at I_C/I_B = 10 ensure low conduction loss in driver applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration
I_C	1.5 A - Continuous collector current handling capacity under specified thermal conditions
P_D @ T_C = 25°C	12.5 W - Power dissipation limit when case temperature is maintained at 25°C via heatsink
h_FE	25–250 - DC current gain range across 5 mA to 500 mA collector current, enabling predictable bias design
V_CE(sat)	≤ 0.5 V @ I_C = 0.5 A, I_B = 0.05 A - Low saturation voltage minimizes power loss in switching or saturated driver use
R_JC	10 °C/W - Thermal resistance from junction to case, critical for heatsink sizing in high-duty-cycle operation

Pinout & Package

BD135 is housed in a TO-225 package (Case 77-09, Style 1) with three leads and an electrically connected metal tab (pins 2 and 4 both connect to collector). The package supports mechanical mounting via the collector tab for thermal and electrical grounding.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Emitter	Main current exit path; referenced for base drive and often tied to ground or emitter resistor in common-emitter amplifiers
Pins 2 & 4	Collector	High-current input node; electrically and thermally connected to metal tab for heatsink attachment
Pin 3	Base	Control terminal for current amplification; requires current-limited drive due to h_FE-dependent I_B requirements

Key Features

Feature	Design Value
High DC current gain	h_FE ≥ 40 at I_C = 150 mA ensures stable bias point with minimal base drive current
Complementary pairing	BD135G is explicitly designated complementary to BD136G (PNP), enabling matched push-pull stage design
Pb-Free / RoHS compliance	G-suffix confirms lead-free plating and halogen-free/BFR-free construction per EU RoHS Directive 2011/65/EU
Thermal performance	R_JC = 10°C/W allows efficient heat transfer to external heatsink, supporting continuous 12.5 W operation at T_C = 25°C

Applications

Audio Power Amplifier Output Stage	DC Motor Driver Stage
Use Scenario: Final output stage in 5–15 W linear audio amplifiers driving 4–8 Ω speakers. IC Role / Device Role / Timing Role: NPN power transistor in complementary pair with BD136G, delivering amplified current to load. Use Value: 45 V_CEO and 1.5 A I_C support ±18 V supply rails; low V_CE(sat) reduces thermal stress during high-current peaks.	Use Scenario: H-bridge or single-ended driver for small brushed DC motors (e.g., fans, actuators) up to 24 V. IC Role / Device Role / Timing Role: Switching or linear current-control element in motor control path, often paired with flyback diode protection. Use Value: 12.5 W dissipation and robust SOA enable reliable operation under stall or PWM transient loads without thermal runaway.
Linear Voltage Regulator Pass Element	Signal-Level Current Booster
Use Scenario: Series pass transistor in adjustable linear regulators supplying 1–1.2 A loads (e.g., lab bench supplies). IC Role / Device Role / Timing Role: High-current series regulator element controlled by error amplifier feedback loop. Use Value: h_FE ≥ 25 at low I_C ensures stable regulation at light loads; R_JC = 10°C/W simplifies heatsink selection for 5–10 W dropout dissipation.	Use Scenario: Boosting current drive capability of op-amp or microcontroller outputs for LED arrays or relay coils. IC Role / Device Role / Timing Role: Emitter-follower buffer providing low-impedance, high-current output while preserving voltage level. Use Value: V_BE(on) ≤ 1.0 V ensures minimal voltage drop; 1.5 A I_C rating supports >500 mA sustained output with margin.

Audio Power Amplifier Output Stage

DC Motor Driver Stage

Use Scenario: Final output stage in 5–15 W linear audio amplifiers driving 4–8 Ω speakers.

IC Role / Device Role / Timing Role: NPN power transistor in complementary pair with BD136G, delivering amplified current to load.

Use Value: 45 V_CEO and 1.5 A I_C support ±18 V supply rails; low V_CE(sat) reduces thermal stress during high-current peaks.

Use Scenario: H-bridge or single-ended driver for small brushed DC motors (e.g., fans, actuators) up to 24 V.

IC Role / Device Role / Timing Role: Switching or linear current-control element in motor control path, often paired with flyback diode protection.

Use Value: 12.5 W dissipation and robust SOA enable reliable operation under stall or PWM transient loads without thermal runaway.

Linear Voltage Regulator Pass Element

Signal-Level Current Booster

Use Scenario: Series pass transistor in adjustable linear regulators supplying 1–1.2 A loads (e.g., lab bench supplies).

IC Role / Device Role / Timing Role: High-current series regulator element controlled by error amplifier feedback loop.

Use Value: h_FE ≥ 25 at low I_C ensures stable regulation at light loads; R_JC = 10°C/W simplifies heatsink selection for 5–10 W dropout dissipation.

Use Scenario: Boosting current drive capability of op-amp or microcontroller outputs for LED arrays or relay coils.

IC Role / Device Role / Timing Role: Emitter-follower buffer providing low-impedance, high-current output while preserving voltage level.

Use Value: V_BE(on) ≤ 1.0 V ensures minimal voltage drop; 1.5 A I_C rating supports >500 mA sustained output with margin.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BD139G	Higher V_CEO (80 V) and V_CBO (100 V); same TO-225 package and pinout	Supports higher supply rails (±36 V) and wider SOA in switching or inductive load applications	Select BD139G when operating above 45 V or requiring enhanced breakdown margin
MJE13003	Lower V_CEO (40 V), higher h_FE (min 100), TO-126 package (smaller footprint, higher R_JA)	Suitable for compact designs with lower voltage rails and moderate thermal constraints	Choose MJE13003 for space-constrained PCBs where 40 V rating suffices and higher gain improves bias stability

Compared with BD135, BD139G offers extended voltage headroom without layout change, while MJE13003 trades voltage margin for smaller size and higher gain-both require verification of thermal interface and SOA under actual load conditions.

Availability

BD135 is available at Aetrix Electronics and suitable for audio amplifier output stages, DC motor drivers, linear regulator pass elements, and signal-level current boosters requiring stable component supply and long-term industrial availability.

Supply support for BD135 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BD135 belongs to onsemi's legacy medium-power discrete transistor family, engineered specifically for cost-sensitive, thermally demanding linear and switching applications in audio and power control systems.

FAQ

What is the maximum collector-emitter voltage rating for BD135?

The BD135 has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc, tested under I_C = 30 mA and I_B = 0. This rating defines the upper limit for safe operation in common-emitter configuration without avalanche breakdown. Exceeding this voltage risks permanent device failure, especially under inductive load transients. The BD135 datasheet specifies this value unambiguously in the Maximum Ratings table.

Is BD135 pin-compatible with BD139G?

Yes, BD135 is pin-compatible with BD139G: both use TO-225 package (Case 77-09, Style 1) with identical pin 1 (emitter), pins 2 & 4 (collector), and pin 3 (base) assignments. However, BD139G has higher voltage ratings (V_CEO = 80 V, V_CBO = 100 V) and identical thermal specs. Substitution is mechanically seamless but requires circuit validation for voltage margin and SOA.

What is the typical DC current gain (h_FE) of BD135 at 150 mA collector current?

At I_C = 150 mA and V_CE = 2 V, the BD135 guarantees h_FE ≥ 40 (minimum) with no upper limit specified. Typical values range up to 250 depending on unit variation and temperature. This gain enables predictable base current calculation (e.g., ~3.75 mA I_B for 150 mA I_C at h_FE = 40), critical for stable bias network design in BD135 amplifier stages.

Does BD135 require a heatsink in normal operation?

Yes, BD135 requires a heatsink when dissipating more than ~1.25 W continuously at ambient temperature, because its R_JA is 100°C/W. At full 12.5 W dissipation, junction temperature would exceed 150°C without case temperature control. The datasheet specifies 12.5 W rating only at T_C = 25°C - meaning effective heatsinking must maintain the case near 25°C. For most linear applications, a modest aluminum heatsink is mandatory for BD135 reliability.

Is BD135 suitable for switching applications?

BD135 can be used in low-frequency switching (≤ 10 kHz) such as relay drivers or PWM motor control, provided saturation is ensured (I_B ≥ I_C/10) and SOA limits are respected. Its 0.5 V V_CE(sat) and 10°C/W R_JC support efficient conduction, but it lacks optimized switching speed specs (e.g., t_f, t_r). For high-speed or high-efficiency switching, dedicated MOSFETs or faster BJTs like MMBT5551 are preferred over BD135.

BD135 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 45 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:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

BD135 FAQ

1.How can I place an order for BD135 through Aetrix?

Please submit a Request for Quotation (RFQ) for BD135 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 BD135 reliable?

The price and inventory of BD135 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BD135 is usually 5 days.

3.What payment methods are accepted for BD135?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BD135 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BD135?

BD135 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BD135 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 BD135?

For technical support, including BD135 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BD135 requirements.

6.How does Aetrix verify that BD135 is sourced from the original manufacturer or authorized distributors?

All BD135 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 BD135 meets industry standards.

7.What is the process for return or replacement of BD135?

All BD135 units undergo pre-shipment inspection (PSI). If there is an issue with BD135, 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 BD135 part is unused and in its original packaging.

Return procedure for BD135:

1.Submit a request within 90 days.

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

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