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

Nexperia USA Inc. MJD31CJ

Name: MJD31CJ
Brand: Nexperia USA Inc.
SKU: MJD31CJ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJD31CJ

Manufacturer:: Nexperia USA Inc.

Category:: Single Bipolar Transistors

Package:: TO-252-3, DPAK (2 Leads + Tab), SC-63

Datasheet:: MJD31CJ.pdf

Description:: TRANS NPN 100V 3A DPAK

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MJD31CJ from Nexperia is an NPN high-power bipolar transistor in DPAK (SOT428C) package, rated for 100 V V_CEO, 3 A continuous collector current, and 15 W junction-to-mounting-base power dissipation. It serves as a robust load switch or linear regulator pass device in industrial power management systems requiring stable thermal performance under sustained conduction.

For engineers reviewing the MJD31CJ datasheet, MJD31CJ pinout, MJD31CJ application, or MJD31CJ equivalent, this page delivers verified electrical parameters, validated thermal resistance values (R_th(j-mb) = 9 K/W), mounting-base-integrated collector topology, and real-world use cases in motor drive and constant-current backlighting circuits.

Technical Context

This transistor operates in active, saturation, and cutoff regions with DC current gain (h_FE) ranging from 10 to 50 at I_C = 3 A and V_CE = 4 V. Its low V_CE(sat) of ≤1.2 V at I_C = 3 A and I_B = 375 mA enables efficient switching and minimal conduction loss in medium-power linear applications.

The device features a thermally optimized DPAK package where the mounting base (Pin 3) is electrically connected to the collector, enabling direct heatsinking. Thermal resistance from junction to mounting base is 9 K/W, while junction-to-ambient (on FR4 PCB) is 79 K/W - confirming its suitability for board-level thermal management without external heatsinks in moderate-duty cycles.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - Maximum safe collector-emitter voltage with base open; defines upper rail limit in high-side switch or linear regulator designs.
I_C	3 A continuous - Sustained collector current rating; determines maximum load current capability in relay replacement or motor drive stages.
V_CE(sat)	≤1.2 V at I_C = 3 A, I_B = 375 mA - Low saturation voltage minimizes power loss (P_loss ≈ 3.6 W) during on-state operation.
h_FE	10–50 at I_C = 3 A - Wide DC gain range informs base drive design margin; supports fixed-bias or emitter-follower configurations.
R_th(j-mb)	9 K/W - Confirmed thermal resistance from junction to mounting base; enables direct thermal coupling to heatsink or copper pour.
P_tot (j-mb)	15 W at T_mb ≤ 25 °C - Total power dissipation limit when mounting base is held at 25 °C; sets absolute thermal ceiling for continuous operation.
f_T	3 MHz - Transition frequency indicates usable bandwidth for analog amplification or fast-switching control loops up to ~300 kHz.

Pinout & Package

Package: DPAK (SOT428C), surface-mounted plastic package with 3 leads (one lead cropped); mounting base (Pin 3) is electrically tied to collector and serves as primary thermal path.

Pin/Terminal	Circuit Role	Design Meaning
1	Base (B)	Control terminal; requires ≥375 mA base drive for full saturation at 3 A collector current.
2	Collector (C)	Main current input; internally bonded to mounting base (Pin 3) for low-inductance, low-resistance thermal and electrical connection.
3	Mounting Base / Collector (mb/C)	Exposed metal pad soldered to PCB copper pour; provides dominant thermal path (R_th(j-mb) = 9 K/W) and structural mechanical anchor.

Key Features

Feature	Design Value
High thermal power dissipation capability	15 W junction-to-mounting-base rating enables sustained operation without external heatsink in compact industrial PCB layouts.
Low collector-emitter saturation voltage	V_CE(sat) ≤ 1.2 V at 3 A ensures <3.6 W conduction loss, reducing thermal stress in linear-mode voltage regulators and constant-current drivers.
Electrically similar to MJD31 series	Pin-compatible and parameter-consistent with legacy MJD31 variants, simplifying drop-in upgrades in existing power stage designs.
Fast switching speeds	f_T = 3 MHz supports sub-microsecond turn-on/turn-off transitions, suitable for PWM-driven motor control and backlight dimming at kHz frequencies.

Applications

Power Management

Load Switch

Use Scenario: Regulating 24 V DC bus voltage for industrial sensors using linear pass configuration.

IC Role / Device Role / Timing Role: NPN pass transistor operating in linear mode, dissipating excess voltage as heat while maintaining precise output regulation.

Use Value: Low V_CE(sat) and high h_FE minimize base drive complexity and improve thermal efficiency over discrete alternatives.

Use Scenario: Enabling/disabling 12 V solenoid loads in programmable logic controllers (PLCs).

IC Role / Device Role / Timing Role: High-current NPN switch controlled by microcontroller GPIO, replacing electromechanical relays.

Use Value: 3 A continuous rating and 5 A peak current support reliable actuation of inductive loads without contact wear or bounce.

Motor Drive

Constant Current Backlighting

Use Scenario: Driving small DC brush motors (e.g., fans, pumps) in HVAC control modules.

IC Role / Device Role / Timing Role: Low-side switching element in H-bridge half-bridge stage, handling bidirectional current flow with fast turn-off.

Use Value: 3 MHz f_T and low storage time enable clean PWM commutation up to 20 kHz, reducing audible noise and EMI.

Use Scenario: Providing stable 350 mA current to LED strings in medical display backlights.

IC Role / Device Role / Timing Role: Constant-current source configured in emitter-follower topology with precision sense resistor feedback.

Use Value: Tight h_FE tolerance (10–50) and low V_BE drift ensure ±3% current regulation across temperature (-55 °C to 150 °C).

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ON Semiconductor MJD31C	Identical V_CEO (100 V), I_C (3 A), and DPAK package; h_FE min = 10 vs. Nexperia's 10–50 typical range; R_th(j-mb) = 8.3 K/W.	Slightly lower thermal resistance improves margin in high-derating scenarios but lacks Nexperia's documented 15 W P_tot (j-mb) rating.	Select when prioritizing worst-case thermal margin over guaranteed power dissipation ceiling.
STMicroelectronics BD237	Higher V_CEO (100 V), same I_C (3 A), TO-126 package; h_FE = 25–250; no integrated mounting base; R_th(j-a) = 50 K/W (with heatsink).	Requires external heatsink and through-hole assembly; unsuitable for space-constrained SMT-only designs.	Choose only if legacy through-hole layout or wider h_FE spread is required for analog gain stability.

Compared with ON Semi MJD31C and ST BD237, the Nexperia MJD31CJ offers superior board-level thermal integration via its mounting-base-connected collector and guaranteed 15 W junction-to-mounting-base dissipation - making it optimal for SMT-based industrial power stages where heatsink real estate is constrained.

Availability

MJD31CJ is available at Aetrix Electronics and suitable for industrial power management, motor drive, constant-current LED backlighting, and relay replacement applications requiring stable component supply and consistent thermal performance across production batches.

Supply support for MJD31CJ 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability standard products including logic, discretes, MOSFETs, and bipolar transistors for automotive, industrial, and consumer markets.

The MJD31CJ belongs to Nexperia's high-power bipolar transistor family, engineered for robust thermal performance and repeatable switching behavior in industrial-grade power conversion and load control applications.

FAQ

Is MJD31CJ pin-compatible with older MJD31 series transistors?

Yes - MJD31CJ uses the DPAK (SOT428C) package with identical pin 1 (base), pin 2 (collector), and pin 3 (mounting base/collector) arrangement as the original MJD31 series. Electrical characteristics including V_CEO, I_C, and h_FE fall within the same specification ranges, enabling direct replacement without layout changes.

What is the maximum allowable junction temperature and how is it enforced?

The absolute maximum junction temperature (T_j) is 150 °C per IEC 60134. This limit is enforced by respecting the derated power dissipation curve: P_tot drops linearly from 15 W at T_mb = 25 °C to zero at T_mb = 150 °C. Maintaining mounting base temperature below 100 °C ensures safe operation at ≥7.5 W continuous dissipation.

Can MJD31CJ be used in avalanche mode for inductive load protection?

No - MJD31CJ is not rated for repetitive avalanche energy. Its datasheet specifies only V_CEO (100 V) as the maximum collector-emitter voltage with base open; no E_AS or ruggedness data is provided. For inductive switching, external flyback diodes or snubbers must be used to clamp voltage spikes below 100 V.

How does the mounting base connection affect PCB layout and thermal design?

The mounting base (Pin 3) is electrically tied to the collector and must be soldered to a minimum 1 cm² copper pour on the PCB's top layer. This copper area acts as both thermal sink and current return path. Thermal vias to inner ground planes are recommended, but isolation from other nets is critical since the base is at collector potential - not ground.

MJD31CJ Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: -

Package/Case:: TO-252-3, DPAK (2 Leads + Tab), SC-63

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 100 V

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

Current - Collector Cutoff (Max):: 1µA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 25 @ 1A, 4V

Power - Max:: 1.6 W

Frequency - Transition:: 3MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DPAK

MJD31CJ FAQ

1.How can I place an order for MJD31CJ through Aetrix?

Please submit a Request for Quotation (RFQ) for MJD31CJ 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 MJD31CJ reliable?

The price and inventory of MJD31CJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJD31CJ is usually 5 days.

3.What payment methods are accepted for MJD31CJ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJD31CJ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJD31CJ?

MJD31CJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJD31CJ 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 MJD31CJ?

For technical support, including MJD31CJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJD31CJ requirements.

6.How does Aetrix verify that MJD31CJ is sourced from the original manufacturer or authorized distributors?

All MJD31CJ 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 MJD31CJ meets industry standards.

7.What is the process for return or replacement of MJD31CJ?

All MJD31CJ units undergo pre-shipment inspection (PSI). If there is an issue with MJD31CJ, 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 MJD31CJ part is unused and in its original packaging.

Return procedure for MJD31CJ:

1.Submit a request within 90 days.

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

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