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

onsemi MJE171

Name: MJE171
Brand: onsemi
SKU: MJE171
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJE171

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: MJE171.pdf

Description:: TRANS PNP 60V 3A TO-126

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MJE171 from onsemi is a PNP silicon power transistor in TO-225 package, rated for 60 V_CEO, 3.0 A continuous collector current, and 12.5 W power dissipation at T_C = 25°C, designed for low-power audio amplifiers and high-speed switching in industrial control circuits.

For engineers reviewing the MJE171 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal limits, safe operating area boundaries, and complementary device pairing guidance specific to the MJE171G variant.

Technical Context

The MJE171 operates as a medium-power PNP bipolar junction transistor with annular construction to minimize leakage currents and supports DC current gain (h_FE) of 50–250 across 100 mA–1.5 A collector current range. Its f_T of 50 MHz enables use in low-frequency switching up to ~10 MHz with controlled turn-on/turn-off times.

Thermal design is constrained by R_JC = 10°C/W and R_JA = 83.4°C/W, requiring heatsinking for sustained >1.5 A operation. Safe operating area (SOA) curves confirm second-breakdown-limited performance up to 60 V_CE and 3 A under pulsed conditions with duty cycle ≤10%.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 Vdc - Maximum collector-emitter voltage before breakdown under open-base condition; defines usable rail voltage headroom in linear amplifier or switch designs.
I_C (continuous)	3.0 Adc - Continuous collector current rating at T_C = 25°C; derates linearly above 25°C at 12 mW/°C when mounted on heatsink.
P_D (T_C)	12.5 W - Maximum power dissipation at case temperature 25°C; requires thermal interface and heatsink to sustain full current at elevated ambient.
h_FE @ I_C = 100 mA	50–250 - DC current gain range enabling stable biasing in Class-A audio stages or predictable switching thresholds in driver circuits.
f_T	50 MHz - Current-gain-bandwidth product confirming suitability for audio-frequency amplification and sub-10 MHz digital switching applications.
V_CE(sat) @ I_C = 1.5 A	0.9 Vdc - Low saturation voltage reduces conduction loss in saturated-switch configurations, improving efficiency in relay drivers or power stage controls.
R_JA	83.4°C/W - Junction-to-ambient thermal resistance without heatsink; limits usable continuous power to ~1.5 W at 25°C ambient without forced cooling.

Pinout & Package

Package: TO-225 (Case 77-09, Style 1), plastic-encapsulated, Pb-free, UL 94 V-0 compliant at 0.125 in thickness. Mounting tab is electrically connected to collector.

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Main current exit path; connects to ground or low-side reference in common-emitter configurations; polarity defines PNP operation.
2, 4	Collector	Main current entry path; internally bonded to metal tab; must be electrically isolated from heatsink unless circuit design permits collector-to-chassis connection.
3	Base	Control terminal for forward-biasing the base-emitter junction; requires current-limiting resistor to deliver specified I_B for target I_C.

Key Features

Feature	Design Value
High DC current gain (h_FE)	50–250 across 100 mA–1.5 A range enables stable biasing without complex feedback networks in discrete amplifier stages.
High f_T (50 MHz)	Supports clean square-wave switching up to ~5 MHz and preserves audio signal integrity through minimal phase shift in preamp or driver roles.
Annular construction	Reduces I_CBO and I_EBO leakage to ≤0.1 mA, improving thermal stability and reducing standby current in battery-powered or precision bias circuits.
TO-225 mechanical robustness	Standardized 3-pin outline with collector-tab mounting allows direct heatsink attachment and simplifies mechanical integration in industrial PCB layouts.
Pb-free / RoHS-compliant	Meets global environmental compliance requirements without compromising thermal or electrical performance; no lead-based solder compatibility concerns.

Applications

Audio Power Amplifier Stage	Low-Voltage Relay Driver
Use Scenario: Final output stage in 5–15 W Class-A/B audio amplifiers driving 4–8 Ω speakers from ±12–24 V rails. IC Role / Device Role / Timing Role: PNP complement to NPN MJE181 in push-pull emitter-follower configuration delivering symmetrical current sourcing/sinking. Use Value: 60 V_CEO and 3 A rating support peak swing beyond ±15 V; h_FE ≥50 ensures stable quiescent current setting with minimal thermal drift.	Use Scenario: Driving 12 VDC coil relays (e.g., 400–800 mW coils) from microcontroller GPIO pins with logic-level enable signals. IC Role / Device Role / Timing Role: Medium-power saturated switch interfacing low-current logic to higher-current inductive loads. Use Value: V_CE(sat) ≤0.9 V at 1.5 A minimizes power loss and self-heating; built-in ESD protection (HBM Class 3B) improves field reliability.
Industrial Motor Control Feedback	Linear Voltage Regulator Pass Element
Use Scenario: Current-sense amplifier front-end in brushed DC motor controllers where bidirectional current monitoring requires matched PNP/NPN pairs. IC Role / Device Role / Timing Role: PNP-side current mirror or differential pair element in analog sensing circuitry operating at <100 kHz bandwidth. Use Value: Matched f_T and h_FE with MJE181 ensure gain symmetry; low Cob (60 pF) maintains signal fidelity in high-impedance feedback paths.	Use Scenario: Series pass transistor in adjustable linear regulators supplying 1–2 A at 5–12 V outputs from unregulated 15–24 V inputs. IC Role / Device Role / Timing Role: High-current, thermally robust series regulator element dissipating up to 12.5 W with external heatsink. Use Value: R_JC = 10°C/W enables efficient heat transfer; SOA curves validate safe operation at 60 V input–output differentials during transient load steps.

Audio Power Amplifier Stage

Low-Voltage Relay Driver

Use Scenario: Final output stage in 5–15 W Class-A/B audio amplifiers driving 4–8 Ω speakers from ±12–24 V rails.

IC Role / Device Role / Timing Role: PNP complement to NPN MJE181 in push-pull emitter-follower configuration delivering symmetrical current sourcing/sinking.

Use Value: 60 V_CEO and 3 A rating support peak swing beyond ±15 V; h_FE ≥50 ensures stable quiescent current setting with minimal thermal drift.

Use Scenario: Driving 12 VDC coil relays (e.g., 400–800 mW coils) from microcontroller GPIO pins with logic-level enable signals.

IC Role / Device Role / Timing Role: Medium-power saturated switch interfacing low-current logic to higher-current inductive loads.

Use Value: V_CE(sat) ≤0.9 V at 1.5 A minimizes power loss and self-heating; built-in ESD protection (HBM Class 3B) improves field reliability.

Industrial Motor Control Feedback

Linear Voltage Regulator Pass Element

Use Scenario: Current-sense amplifier front-end in brushed DC motor controllers where bidirectional current monitoring requires matched PNP/NPN pairs.

IC Role / Device Role / Timing Role: PNP-side current mirror or differential pair element in analog sensing circuitry operating at <100 kHz bandwidth.

Use Value: Matched f_T and h_FE with MJE181 ensure gain symmetry; low Cob (60 pF) maintains signal fidelity in high-impedance feedback paths.

Use Scenario: Series pass transistor in adjustable linear regulators supplying 1–2 A at 5–12 V outputs from unregulated 15–24 V inputs.

IC Role / Device Role / Timing Role: High-current, thermally robust series regulator element dissipating up to 12.5 W with external heatsink.

Use Value: R_JC = 10°C/W enables efficient heat transfer; SOA curves validate safe operation at 60 V input–output differentials during transient load steps.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJE172G	Higher V_CEO (80 V) and V_CB (100 V); otherwise identical package, pinout, and gain characteristics.	Suitable for higher-input-voltage regulators or amplifier stages requiring >60 V headroom.	Select MJE172G only if system voltage exceeds 60 V; no layout change needed but may incur higher cost and slightly lower f_T margin.
BD140	Same TO-126 package (not TO-225); lower P_D (1.5 W @ T_A), lower I_C (1.5 A), and lower V_CEO (80 V).	Limited to low-power switching or small-signal amplification where heatsinking is impractical.	Use BD140 only in space-constrained, low-dissipation designs; requires PCB redesign due to different footprint and thermal path.

Compared with MJE171, MJE172G offers extended voltage capability without altering board layout or drive requirements, while BD140 trades power handling for compactness-making MJE171 the optimal balance of voltage, current, thermal performance, and standardization in TO-225 industrial designs.

Availability

MJE171 is available at Aetrix Electronics and suitable for low-power audio amplifiers, relay drivers, industrial motor control feedback circuits, and linear voltage regulator pass elements requiring stable component supply and long-term manufacturability.

Supply support for MJE171 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 is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MJE170/171/172 series belongs to onsemi's legacy silicon power transistor product line, engineered specifically for cost-sensitive, reliability-critical linear and switching applications in industrial control and audio systems.

FAQ

What is the maximum continuous collector current for the MJE171 at 25°C case temperature?

The MJE171 supports a maximum continuous collector current of 3.0 A when the case temperature is maintained at 25°C. This rating assumes proper heatsinking and derates linearly at 12 mW/°C above 25°C. Exceeding this current without thermal management risks junction overheating and permanent degradation of the MJE171.

Is the MJE171 pin-compatible with the MJE181 NPN transistor?

Yes, the MJE171 and MJE181 share identical TO-225 (Case 77-09, Style 1) packaging and pinout: Pin 1 = Emitter (MJE171) / Collector (MJE181), Pin 2 & 4 = Collector (MJE171) / Emitter (MJE181), Pin 3 = Base. This complementary arrangement enables direct use in push-pull amplifier or H-bridge driver topologies without PCB modification.

What is the typical DC current gain (hFE) of the MJE171 at 500 mA collector current?

At I_C = 500 mA and V_CE = 1.0 Vdc, the MJE171 exhibits a DC current gain (h_FE) ranging from 30 to 250 per its datasheet specifications. The minimum guaranteed value is 30, ensuring predictable base drive requirements in switching applications; actual units typically measure 80–150 under these conditions.

Does the MJE171 have built-in ESD protection, and what level is specified?

Yes, the MJE171 is rated for Human Body Model (HBM) ESD protection at Class 3B (≥4 kV), as confirmed in the onsemi datasheet. This level provides robust handling tolerance during assembly and field operation, reducing failure risk in environments with moderate static discharge exposure without requiring external protection components for the MJE171 itself.

Can the MJE171 be used in linear regulator applications, and what thermal considerations apply?

Yes, the MJE171 is commonly used as a series pass element in adjustable linear regulators. With R_JC = 10°C/W and P_D = 12.5 W at T_C = 25°C, it requires a heatsink capable of maintaining case temperature ≤25°C under full load. For example, dissipating 6 W demands a heatsink-to-ambient thermal resistance ≤35°C/W when ambient is 25°C.

MJE171 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):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 60 V

Vce Saturation (Max) @ Ib, Ic:: 1.7V @ 600mA, 3A

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 50 @ 100mA, 1V

Power - Max:: 12.5 W

Frequency - Transition:: 50MHz

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

MJE171 FAQ

1.How can I place an order for MJE171 through Aetrix?

Please submit a Request for Quotation (RFQ) for MJE171 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 MJE171 reliable?

The price and inventory of MJE171 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJE171 is usually 5 days.

3.What payment methods are accepted for MJE171?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJE171 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJE171?

MJE171 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJE171 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 MJE171?

For technical support, including MJE171 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJE171 requirements.

6.How does Aetrix verify that MJE171 is sourced from the original manufacturer or authorized distributors?

All MJE171 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 MJE171 meets industry standards.

7.What is the process for return or replacement of MJE171?

All MJE171 units undergo pre-shipment inspection (PSI). If there is an issue with MJE171, 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 MJE171 part is unused and in its original packaging.

Return procedure for MJE171:

1.Submit a request within 90 days.

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

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