Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

onsemi TIP31

Name: TIP31
Brand: onsemi
SKU: TIP31
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: TIP31

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-220-3

Datasheet:: TIP31.pdf

Description:: TRANS NPN 40V 3A TO-220

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:9,567

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

TIP31 from onsemi is an NPN silicon power transistor in TO−220 package, rated for 40 V_CEO, 3.0 A continuous collector current, and 40 W power dissipation at T_C = 25°C, designed for general-purpose amplifier and switching applications in industrial power supplies and motor control circuits.

For engineers reviewing the TIP31 datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO rating, DC current gain (h_FE ≥25 at I_C = 1.0 A), saturation voltage (V_CE(sat) ≤1.2 V), thermal resistance (R_JC = 3.125 °C/W), and Pb-free TO−220 packaging compliance.

Technical Context

The TIP31 operates as a medium-power bipolar junction transistor with fixed NPN polarity, optimized for linear amplification and hard-switching duty cycles. Its safe operating area (SOA) is defined up to 150°C junction temperature, with secondary breakdown limits validated for pulse widths ≤100 ms and duty cycles ≤10%.

It features a minimum DC current gain of 25 at I_C = 1.0 A and V_CE = 4.0 V, and a current-gain–bandwidth product (f_T) of 3.0 MHz under specified test conditions. Thermal derating is linear at 0.32 W/°C above 25°C case temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines maximum supply rail compatibility in switching designs.
I_C (continuous)	3.0 A - Continuous collector current limit at T_C = 25°C; sets baseline load-handling capability for relay drivers or low-speed PWM stages.
P_D @ T_C = 25°C	40 W - Total power dissipation limit with heatsink; requires thermal interface design to maintain R_JC + R_CA ≤ 12.5 °C/W for safe operation.
h_FE	25–50 - DC current gain range at I_C = 1.0 A / V_CE = 4.0 V; determines required base drive current (e.g., ~60 mA for 1.5 A collector load).
V_CE(sat)	≤1.2 V - Collector-emitter saturation voltage at I_C = 3.0 A / I_B = 375 mA; directly impacts conduction loss and heat generation in saturated switch mode.
f_T	3.0 MHz - Current-gain–bandwidth product at I_C = 500 mA / V_CE = 10 V; constrains usable frequency range in small-signal amplification.

Pinout & Package

Package: TO−220−3 (Case 221A), 10.10 × 15.12 × 4.45 mm, 2.54 mm pin pitch, Pb-free, with pins arranged in Style 1: Pin 1 = Base, Pin 2 = Collector, Pin 3 = Emitter, Pin 4 = Collector (dual-collector configuration).

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Base	Control terminal for forward-bias injection; requires current-limited drive (I_B ≤1.0 A) to avoid damage during saturation.
Pin 2 & Pin 4	Collector	Parallel-connected high-current output terminals; both must be soldered to heatsink plane for thermal integrity and current sharing.
Pin 3	Emitter	Reference node for biasing and feedback; common connection point for emitter resistors or current sensing in amplifier configurations.

Key Features

Feature	Design Value
High current gain–bandwidth product	3.0 MHz f_T enables stable audio-frequency amplification and fast switching up to ~100 kHz with adequate base drive.
Compact TO−220 package	Standardized mechanical footprint allows drop-in replacement in legacy PCBs and compatibility with off-the-shelf heatsinks.
Pb-free and RoHS compliant	Meets EU RoHS Directive 2011/65/EU; eliminates lead-based soldering restrictions and supports environmentally aligned manufacturing.
Unclamped inductive energy rating	32 mJ at I_C = 1.8 A, L = 20 mH - quantifies ruggedness against inductive kickback in relay or solenoid driver applications.

Applications

DC Motor Driver Stage	Linear Power Supply Pass Element
Use Scenario: Driving 24 V, 1.5 A brushed DC motors in industrial actuators using single-ended PWM control. IC Role / Device Role / Timing Role: NPN power switch operating in saturation and cutoff modes; handles bidirectional current only when paired with flyback diode. Use Value: V_CE(sat) ≤1.2 V minimizes conduction loss (≤1.8 W at 1.5 A), while 40 W thermal rating supports intermittent 100% duty cycle with heatsinking.	Use Scenario: Series pass transistor in adjustable 0–30 V, 3 A bench power supply with op-amp error amplifier feedback. IC Role / Device Role / Timing Role: Linear regulator element dissipating variable power based on input-output differential voltage and load current. Use Value: h_FE ≥25 ensures stable closed-loop gain margin; SOA curves validate safe operation across full V_IN–V_OUT range up to 40 V.
Relay Driver Interface	Audio Power Amplifier Output Stage
Use Scenario: Driving 12 V, 500 mA electromagnetic relays from microcontroller GPIO pins via base resistor network. IC Role / Device Role / Timing Role: Digital switch translating logic-level signals into high-current coil activation; operates in cutoff/saturation with no linear region dwell. Use Value: I_C = 3.0 A and V_CEO = 40 V provide 8× safety margin over relay coil requirements, ensuring long-term reliability under surge conditions.	Use Scenario: Complementary Class AB output stage in 10 W audio amplifier feeding 8 Ω speakers with ±20 V rails. IC Role / Device Role / Timing Role: Medium-power output transistor delivering peak current up to 2.5 A with low distortion in linear region. Use Value: f_T = 3.0 MHz supports bandwidth beyond 20 kHz; V_BE(on) ≤1.8 V enables predictable bias network design for thermal stability.

DC Motor Driver Stage

Linear Power Supply Pass Element

Use Scenario: Driving 24 V, 1.5 A brushed DC motors in industrial actuators using single-ended PWM control.

IC Role / Device Role / Timing Role: NPN power switch operating in saturation and cutoff modes; handles bidirectional current only when paired with flyback diode.

Use Value: V_CE(sat) ≤1.2 V minimizes conduction loss (≤1.8 W at 1.5 A), while 40 W thermal rating supports intermittent 100% duty cycle with heatsinking.

Use Scenario: Series pass transistor in adjustable 0–30 V, 3 A bench power supply with op-amp error amplifier feedback.

IC Role / Device Role / Timing Role: Linear regulator element dissipating variable power based on input-output differential voltage and load current.

Use Value: h_FE ≥25 ensures stable closed-loop gain margin; SOA curves validate safe operation across full V_IN–V_OUT range up to 40 V.

Relay Driver Interface

Audio Power Amplifier Output Stage

Use Scenario: Driving 12 V, 500 mA electromagnetic relays from microcontroller GPIO pins via base resistor network.

IC Role / Device Role / Timing Role: Digital switch translating logic-level signals into high-current coil activation; operates in cutoff/saturation with no linear region dwell.

Use Value: I_C = 3.0 A and V_CEO = 40 V provide 8× safety margin over relay coil requirements, ensuring long-term reliability under surge conditions.

Use Scenario: Complementary Class AB output stage in 10 W audio amplifier feeding 8 Ω speakers with ±20 V rails.

IC Role / Device Role / Timing Role: Medium-power output transistor delivering peak current up to 2.5 A with low distortion in linear region.

Use Value: f_T = 3.0 MHz supports bandwidth beyond 20 kHz; V_BE(on) ≤1.8 V enables predictable bias network design for thermal stability.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJE13003	Higher V_CEO (400 V), lower I_C (1.5 A), TO−126 package; f_T = 4 MHz.	Better suited for high-voltage, low-current flyback or SMPS primary switches; not interchangeable without layout change.	Select when >100 V blocking is required and power dissipation is <15 W.
BD139	Lower V_CEO (80 V), same I_C (1.5 A), TO−126 package; h_FE = 40–250 (wide spread).	Preferred for low-cost audio preamps and low-power linear regulators where gain consistency is less critical.	Choose for cost-sensitive consumer audio where 80 V rating suffices and TO−220 footprint is not mandatory.

Compared with MJE13003 and BD139, the TIP31 offers standardized TO−220 mechanical compatibility, guaranteed 3.0 A continuous current, and tighter h_FE binning-making it optimal for industrial-grade switching and amplification where thermal management and pinout consistency are prioritized.

Availability

TIP31 is available at Aetrix Electronics and suitable for DC motor control, linear power supply regulation, and relay interface applications requiring stable component supply and long-term industrial availability.

Supply support for TIP31 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 supplier specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The TIP31 belongs to onsemi's legacy plastic power transistor family, engineered for robustness and manufacturability in cost-sensitive, high-reliability linear and switching power applications.

FAQ

What is the maximum continuous collector current rating for the TIP31?

The TIP31 has a maximum continuous collector current (I_C) rating of 3.0 A at case temperature T_C = 25°C. This rating decreases linearly by 0.32 W/°C above 25°C, and actual usable current depends on heatsink performance and ambient conditions. The TIP31 datasheet specifies I_C = 3.0 A as the absolute limit under ideal thermal management-exceeding this risks thermal runaway or bond-wire failure.

Is the TIP31 pin-compatible with other transistors in the TIP31x series?

Yes, the TIP31 shares identical TO−220 pinout (Style 1: Base–Collector–Emitter–Collector) with TIP31A, TIP31B, and TIP31C variants. However, V_CEO ratings differ: TIP31 = 40 V, TIP31A = 60 V, TIP31B = 80 V, TIP31C = 100 V. Substituting TIP31 for higher-voltage variants requires verifying that system voltage transients remain below 40 V to prevent breakdown.

Does the TIP31 require a heatsink in all applications?

A heatsink is required whenever power dissipation exceeds ~2.0 W at ambient temperature, since the TIP31's R_JA is 62.5 °C/W. At 3.0 A and V_CE(sat) = 1.2 V, conduction loss alone reaches 3.6 W-well above the 2.0 W limit for operation without heatsinking. Even in switching applications with low duty cycle, transient thermal analysis per Figure 4 of the TIP31 datasheet confirms heatsink necessity for reliability.

What is the typical DC current gain (h_FE) of the TIP31 at 1.0 A collector current?

The TIP31 exhibits a minimum h_FE of 25 and a typical value of ~40 at I_C = 1.0 A and V_CE = 4.0 V, per the Electrical Characteristics table. This gain drops to ≥10 at I_C = 3.0 A, meaning base drive must scale accordingly-for example, 100 mA I_B is needed to sustain 3.0 A I_C with h_FE = 30. The TIP31 datasheet provides h_FE vs. I_C curves (Figure 8) confirming this behavior.

Can the TIP31 be used in audio amplifier output stages?

Yes, the TIP31 is commonly used in Class AB audio output stages up to ~10 W into 8 Ω loads. Its f_T = 3.0 MHz supports full audio bandwidth, and V_BE(on) ≤1.8 V enables stable bias network design. However, due to its relatively wide h_FE tolerance and SOA limitations at high V_CE/I_C combinations, it is best applied in non-critical, medium-fidelity designs-not high-end Hi-Fi where matched complementary pairs (e.g., TIP31/TIP32) and precise thermal tracking are essential.

TIP31 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 3 A

Voltage - Collector Emitter Breakdown (Max):: 40 V

Vce Saturation (Max) @ Ib, Ic:: 1.2V @ 375mA, 3A

Current - Collector Cutoff (Max):: 300µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 10 @ 3A, 4V

Power - Max:: 2 W

Frequency - Transition:: 3MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

TIP31 FAQ

1.How can I place an order for TIP31 through Aetrix?

Please submit a Request for Quotation (RFQ) for TIP31 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 TIP31 reliable?

The price and inventory of TIP31 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TIP31 is usually 5 days.

3.What payment methods are accepted for TIP31?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TIP31 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TIP31?

TIP31 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TIP31 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 TIP31?

For technical support, including TIP31 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TIP31 requirements.

6.How does Aetrix verify that TIP31 is sourced from the original manufacturer or authorized distributors?

All TIP31 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 TIP31 meets industry standards.

7.What is the process for return or replacement of TIP31?

All TIP31 units undergo pre-shipment inspection (PSI). If there is an issue with TIP31, 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 TIP31 part is unused and in its original packaging.

Return procedure for TIP31:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…