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

onsemi MJE171G

Name: MJE171G
Brand: onsemi
SKU: MJE171G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJE171G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: MJE171G.pdf

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

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MJE171G from onsemi is a PNP silicon power transistor designed for low-power audio amplifiers and low-current, high-speed switching applications. It features 60 V_CEO, 3.0 A continuous collector current, 12.5 W power dissipation at T_C = 25°C, DC current gain (h_FE) of 30 at I_C = 500 mA, and f_T = 50 MHz - enabling reliable operation in Class-B audio output stages and relay drivers.

For engineers reviewing the MJE171G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, TO-225 package mapping, thermal derating behavior, safe operating area limits, and validated alternatives for discrete PNP power transistor selection in industrial and audio signal paths.

Technical Context

The MJE171G operates as a medium-power PNP bipolar junction transistor with annular construction to minimize leakage and improve thermal stability. Its 60 V_CEO rating and 3.0 A I_C support linear amplification up to ~10 W into 8 Ω loads and fast switching with t_on < 200 ns and t_off < 300 ns under specified test conditions.

Thermal design is constrained by R_JC = 10 °C/W and R_JA = 83.4 °C/W, requiring heatsinking for sustained >1.5 W dissipation. Safe operating area (SOA) curves confirm second-breakdown-limited performance below 60 V_CE, with pulse capability extending beyond DC ratings when duty cycle ≤10% and T_J(pk) ≤150°C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	60 Vdc - Maximum collector-emitter voltage before breakdown under open-base conditions; defines usable supply rail headroom in amplifier or switch designs.
I_C (continuous)	3.0 Adc - Sustained collector current limit at T_C = 25°C; sets maximum linear output current in Class-A/B audio stages.
P_D @ T_C = 25°C	12.5 W - Peak junction-to-case power dissipation; requires mechanical heatsink interface for >1.5 W ambient operation.
h_FE @ I_C = 500 mA	30 (min) - DC current gain at mid-range current; determines base drive requirement for saturation in switching applications.
f_T	50 MHz - Current-gain-bandwidth product at I_C = 100 mA, V_CE = 10 V; supports stable operation up to ~5–10 MHz small-signal amplification.
V_CE(sat) @ I_C = 1.5 A	0.9 Vdc - Collector-emitter saturation voltage at high current; directly impacts conduction loss and thermal rise in switching regulators.
R_JA	83.4 °C/W - Junction-to-ambient thermal resistance in free-air; establishes minimum PCB copper area or heatsink size for thermal compliance.

Pinout & Package

Package: TO-225 (Case 77-09, Style 1), plastic-encapsulated, Pb-free, UL 94 V-0 compliant. Mounting tab is electrically connected to collector (pins 2 and 4).

Pin/Terminal	Circuit Role	Design Meaning
1	Emitter	Main current exit path for PNP device; connects to load return or ground reference in common-emitter configurations.
2, 4	Collector	Primary current input node; pins 2 and 4 are internally bonded to same collector structure and share mounting tab connection.
3	Base	Control terminal for bipolar conduction; requires current-limited drive (≤1.0 A) to avoid damage during switching transients.

Key Features

Feature	Design Value
High DC current gain	h_FE ≥ 30 at I_C = 500 mA - reduces required base drive current and simplifies driver stage design in discrete amplifier circuits.
High f_T	50 MHz - enables stable small-signal amplification and fast switching up to ~10 MHz without significant gain roll-off.
Annular construction	Minimizes I_CBO and I_EBO leakage - improves bias stability over temperature in precision analog and low-power linear applications.
TO-225 mechanical robustness	12.5 W power handling with 10 °C/W R_JC - allows direct bolt-down heatsinking for thermally demanding Class-B output stages.
Pb-free & RoHS compliant	G-suffix indicates lead-free termination and UL 94 V-0 epoxy - meets global environmental compliance requirements for industrial and consumer end equipment.

Applications

Audio Power Amplifier Output Stage	Relay / Solenoid Driver
Use Scenario: Complementary Class-B push-pull output stage in 5–10 W audio amplifiers driving 4–8 Ω speakers. IC Role / Device Role / Timing Role: PNP power transistor delivering negative half-cycle current; paired with NPN MJE181G for full-wave amplification. Use Value: 60 V_CEO and 3.0 A I_C enable clean clipping-free output into 8 Ω at ±24 V rails; h_FE ≥ 30 ensures predictable bias current setting.	Use Scenario: High-side switch controlling 12–24 V DC relays or solenoids in PLC I/O modules and industrial control panels. IC Role / Device Role / Timing Role: PNP switch sinking load current through emitter to V_CC; base driven by microcontroller GPIO via current-limiting resistor. Use Value: V_CE(sat) ≤ 0.9 V at 1.5 A minimizes power loss and self-heating; 50 MHz f_T supports <1 µs turn-on/turn-off for fast actuation sequencing.
DC Motor Speed Control	Linear Voltage Regulator Pass Element
Use Scenario: Low-frequency PWM-driven H-bridge half-bridge leg for 3–6 W brushed DC motors in instrumentation and lab equipment. IC Role / Device Role / Timing Role: PNP high-side switch in complementary emitter-follower configuration; handles bidirectional current during braking. Use Value: SOA curve supports 60 V/1.5 A pulses at 10% duty cycle; R_JC = 10 °C/W enables compact heatsink integration on motor driver PCBs.	Use Scenario: Series pass transistor in adjustable linear regulators delivering up to 2.5 A at 5–15 V output with low dropout margin. IC Role / Device Role / Timing Role: PNP pass element operating in active region; base controlled by error amplifier to regulate output voltage. Use Value: h_FE ≥ 12 at I_C = 1.5 A ensures stable loop gain; V_CEO = 60 V accommodates 48 V input rails with safety margin.

Audio Power Amplifier Output Stage

Relay / Solenoid Driver

Use Scenario: Complementary Class-B push-pull output stage in 5–10 W audio amplifiers driving 4–8 Ω speakers.

IC Role / Device Role / Timing Role: PNP power transistor delivering negative half-cycle current; paired with NPN MJE181G for full-wave amplification.

Use Value: 60 V_CEO and 3.0 A I_C enable clean clipping-free output into 8 Ω at ±24 V rails; h_FE ≥ 30 ensures predictable bias current setting.

Use Scenario: High-side switch controlling 12–24 V DC relays or solenoids in PLC I/O modules and industrial control panels.

IC Role / Device Role / Timing Role: PNP switch sinking load current through emitter to V_CC; base driven by microcontroller GPIO via current-limiting resistor.

Use Value: V_CE(sat) ≤ 0.9 V at 1.5 A minimizes power loss and self-heating; 50 MHz f_T supports <1 µs turn-on/turn-off for fast actuation sequencing.

DC Motor Speed Control

Linear Voltage Regulator Pass Element

Use Scenario: Low-frequency PWM-driven H-bridge half-bridge leg for 3–6 W brushed DC motors in instrumentation and lab equipment.

IC Role / Device Role / Timing Role: PNP high-side switch in complementary emitter-follower configuration; handles bidirectional current during braking.

Use Value: SOA curve supports 60 V/1.5 A pulses at 10% duty cycle; R_JC = 10 °C/W enables compact heatsink integration on motor driver PCBs.

Use Scenario: Series pass transistor in adjustable linear regulators delivering up to 2.5 A at 5–15 V output with low dropout margin.

IC Role / Device Role / Timing Role: PNP pass element operating in active region; base controlled by error amplifier to regulate output voltage.

Use Value: h_FE ≥ 12 at I_C = 1.5 A ensures stable loop gain; V_CEO = 60 V accommodates 48 V input rails with safety margin.

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, lower h_FE = 12 at I_C = 1.5 A, same TO-225 package and pinout.	Better suited for higher-voltage supplies (>36 V) but requires larger base drive for equivalent current.	Select MJE172G when system rail exceeds 48 V and SOA must extend beyond 60 V; otherwise MJE171G offers superior gain-efficiency trade-off.
BD140	V_CEO = 80 V, I_C = 1.5 A, h_FE = 40 min at I_C = 150 mA, TO-126 package (smaller footprint, higher R_JA).	Limited to ≤1.5 A continuous; unsuitable for 3 A load peaks without derating; not drop-in due to different pinout and thermal profile.	Choose BD140 only for space-constrained, lower-current (<1.2 A) applications where TO-126 mounting is preferred; verify SOA compliance at target V_CE.

Compared with MJE172G and BD140, the MJE171G provides optimal balance of 60 V rating, 3.0 A current capability, and 30× DC gain - making it the preferred choice for 24–48 V industrial amplifiers and drivers where thermal management and base drive efficiency are critical.

Availability

MJE171G is available at Aetrix Electronics and suitable for audio amplifier output stages, relay/solenoid drivers, and DC motor speed controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MJE171G 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 MJE170/171/172G series belongs to onsemi's legacy silicon power transistor family, engineered specifically for low-power audio amplification and high-speed switching in cost-sensitive industrial controls and instrumentation.

FAQ

What is the maximum continuous collector current for MJE171G?

The MJE171G supports 3.0 A continuous collector current (I_C) at case temperature T_C = 25°C. Derating applies above 25°C at 0.012 W/°C - meaning usable current drops to ~2.4 A at T_C = 75°C. This rating assumes proper heatsinking per the 10 °C/W R_JC specification. The MJE171G must not exceed its SOA limits under pulsed conditions.

Is MJE171G pin-compatible with MJE172G?

Yes, the MJE171G and MJE172G share identical TO-225 (Case 77-09, Style 1) packaging and pinout: Pin 1 = Emitter, Pins 2 & 4 = Collector, Pin 3 = Base. Both devices mount identically and require no PCB layout changes. However, MJE172G has higher V_CEO (80 V vs. 60 V) and lower h_FE (12 vs. 30 at I_C = 1.5 A), so functional substitution requires verification of gain and voltage margin in the target circuit.

What is the safe operating area (SOA) limitation for MJE171G at 30 V_CE?

At V_CE = 30 V, the MJE171G's SOA curve (Figure 5) permits up to ~2.2 A DC current or ~3.5 A for 10 ms pulses (10% duty cycle). Operation beyond these boundaries risks second breakdown or thermal runaway. The SOA is thermally limited at low V_CE and second-breakdown limited above ~20 V_CE. Always consult Figure 5 in the official MJE171/D datasheet for precise boundary values.

Does MJE171G have built-in ESD protection?

The MJE171G is rated for ESD-HBM Class 3B (≥4 kV) per JEDEC JS-001, but it does not include integrated ESD protection diodes. System-level protection (e.g., series resistors, TVS diodes) is recommended at base and emitter terminals in environments with handling or operational ESD risk. The "3B" rating reflects device robustness during manufacturing handling, not functional immunity during end-use operation.

Can MJE171G be used in complementary pairs with NPN transistors?

Yes - the MJE171G is explicitly designed as the PNP complement to the NPN MJE181G (same V_CEO = 60 V, I_C = 3.0 A, TO-225 package). Their matched parameters enable symmetrical Class-B audio output stages and balanced switching bridges. Pairing with non-matched NPNs (e.g., 2N3055) introduces gain and thermal mismatch, degrading linearity and reliability.

MJE171G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Active

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:: 1.5 W

Frequency - Transition:: 50MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-126

MJE171G FAQ

1.How can I place an order for MJE171G through Aetrix?

Please submit a Request for Quotation (RFQ) for MJE171G 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 MJE171G reliable?

The price and inventory of MJE171G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJE171G is usually 5 days.

3.What payment methods are accepted for MJE171G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJE171G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJE171G?

MJE171G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJE171G 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 MJE171G?

For technical support, including MJE171G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJE171G requirements.

6.How does Aetrix verify that MJE171G is sourced from the original manufacturer or authorized distributors?

All MJE171G 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 MJE171G meets industry standards.

7.What is the process for return or replacement of MJE171G?

All MJE171G units undergo pre-shipment inspection (PSI). If there is an issue with MJE171G, 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 MJE171G part is unused and in its original packaging.

Return procedure for MJE171G:

1.Submit a request within 90 days.

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

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