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

STMicroelectronics MJD31CT4-A

Name: MJD31CT4-A
Brand: STMicroelectronics
SKU: MJD31CT4-A
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MJD31CT4-A

Manufacturer:: STMicroelectronics

Category:: Single Bipolar Transistors

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

Datasheet:: MJD31CT4-A.pdf

Description:: TRANS NPN 100V 3A DPAK

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Product details

Overview

MJD31CT4-A from STMicroelectronics is an AEC-Q101-qualified NPN power transistor in DPAK (TO-252) surface-mount package, rated for 100 V V_CEO, 3 A continuous collector current, and 15 W power dissipation at T_C = 25 °C; it delivers low V_CE(sat) of 1.2 V at I_C = 3 A / I_B = 375 mA and high h_FE up to 50, enabling efficient linear regulation and switching in automotive body control modules.

For engineers reviewing the MJD31CT4-A datasheet, MJD31CT4-A pinout, MJD31CT4-A application, or MJD31CT4-A equivalent, key selection criteria include its AEC-Q101 qualification, DPAK thermal performance (R_thJC = 8.3 °C/W), V_CE(sat) stability under pulse load, and complementary pairing with MJD32CT4-A for H-bridge driver stages.

Technical Context

This planar silicon NPN transistor uses a "base island" layout to achieve high DC current gain (h_FE = 25–50 at I_C = 1–3 A) while maintaining low saturation voltage (V_CE(sat) ≤ 1.2 V). Its safe operating area supports resistive load switching with t_on/t_off curves documented per Figure 8–9 of DS5255.

The device operates across –65 °C to 150 °C junction temperature range and features V_CEO(sus) = 100 V under sustaining conditions, making it suitable for inductive load switching where voltage transients exceed standard V_CEO ratings.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	100 V - Sustains full-rated collector-emitter voltage with zero base current, enabling direct drive of 24 V automotive loads with margin.
I_C (cont.)	3 A - Continuous collector current rating at T_C = 25 °C; derates linearly above 25 °C per Figure 2.
V_CE(sat)	1.2 V max @ I_C = 3 A, I_B = 375 mA - Minimizes conduction loss in high-current switching paths (e.g., fan drivers).
h_FE	25–50 @ I_C = 1–3 A - Enables low-base-drive-current operation in linear regulators and gate drivers.
R_thJC	8.3 °C/W - Junction-to-case thermal resistance allows direct heatsinking via PCB copper pour or external heatsink mounting.
AEC-Q101	Qualified - Validated for automotive under-hood applications including temperature cycling, humidity, and mechanical shock per JESD22 standards.

Pinout & Package

The MJD31CT4-A is housed in a DPAK (TO-252) surface-mount package with exposed tab (pin 2) serving as the collector terminal. The package supports tape-and-reel automated assembly and provides 15 W power dissipation capability when mounted on 1 in² FR-4 with 2-oz copper.

Pin/Terminal	Circuit Role	Design Meaning
1 (B)	Base	Control input requiring ~375 mA base current to saturate at 3 A collector load; driven directly by MCU GPIO or logic-level buffer.
2 (TAB/C)	Collector (exposed tab)	Primary power path and thermal interface; must be connected to low-impedance ground plane or heatsink for R_thJC optimization.
3 (E)	Emitter	Current return path; typically tied to system ground or low-side shunt resistor for current sensing.

Key Features

Feature	Design Value
Planar "base island" structure	Enables simultaneous high h_FE and low V_CE(sat) without trade-off-critical for thermally constrained automotive PCBs.
AEC-Q101 qualification	Validated for automotive under-hood use including 1000-cycle temperature cycling (–40 °C to +125 °C) and 1000 h HTOL stress.
DPAK (TO-252) package	Provides 3× higher power density than TO-220 while supporting automated SMT placement and reflow soldering.
Complementary PNP pairing	Matches MJD32CT4-A in electrical specs and thermal profile, simplifying dual-transistor H-bridge or push-pull stage design.

Applications

Automotive Body Control Unit (BCU)

Industrial Fan Speed Controller

Use Scenario: Driving 24 V DC cooling fans in engine bay environments with ambient temperatures up to 105 °C.

IC Role / Device Role / Timing Role: NPN power switch controlling fan motor current; operated in saturated switching mode with PWM frequency < 20 kHz.

Use Value: Low V_CE(sat) reduces heat generation at 3 A load, while AEC-Q101 ensures reliability over 15-year vehicle lifetime.

Use Scenario: Regulating airflow in HVAC blowers using linear current control with feedback loop.

IC Role / Device Role / Timing Role: Linear pass transistor in adjustable current source configuration, dissipating up to 8 W continuously.

Use Value: High h_FE minimizes base drive power; R_thJC = 8.3 °C/W enables stable operation with minimal heatsink area.

DC Motor H-Bridge Half-Bridge Stage

LED Load Driver for Commercial Lighting

Use Scenario: Upper half-bridge switch in 24 V bidirectional DC motor driver for seat/mirror actuation.

IC Role / Device Role / Timing Role: High-side NPN switch paired with MJD32CT4-A as low-side PNP; driven with shoot-through protection.

Use Value: Matched V_CE(sat) and h_FE between complementary pair ensures balanced conduction losses and timing symmetry.

Use Scenario: Constant-current driver for high-brightness LED strings in streetlight fixtures.

IC Role / Device Role / Timing Role: Series-pass element in analog dimming circuit, modulated by 0–10 V control signal.

Use Value: Tight V_BE(on) tolerance (1.8 V typ.) enables accurate current setting across temperature; low ICEO (< 50 μA) prevents LED leakage in off-state.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
ON Semiconductor MJD31C	V_CEO = 100 V, I_C = 3 A, but h_FE min = 20 (vs. 25), R_thJC = 9.0 °C/W (vs. 8.3 °C/W); no AEC-Q101 certification.	Not qualified for automotive; suitable only for industrial linear/switching where qualification is not required.	Select when cost sensitivity outweighs automotive compliance and thermal margin requirements.
Diodes Incorporated ZTX653	V_CEO = 100 V, I_C = 2 A (vs. 3 A), h_FE = 40–120, R_thJC = 10 °C/W; SOT-223 package limits power handling.	Limited to ≤2 A continuous loads; unsuitable for 3 A fan or motor drive; better for low-power LED drivers.	Choose only for space-constrained designs where 2 A rating suffices and DPAK footprint is unavailable.

Compared with MJD31C and ZTX653, the MJD31CT4-A uniquely combines AEC-Q101 qualification, 3 A current capability, and superior thermal resistance in DPAK-making it the only option validated for automotive-grade 24 V power switching with sustained 15 W dissipation.

Availability

MJD31CT4-A is available at Aetrix Electronics and suitable for automotive body control units, industrial fan speed controllers, DC motor H-bridge stages, and LED constant-current drivers requiring stable component supply across multi-year production cycles.

Supply support for MJD31CT4-A 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power transistors, sensors, and analog ICs for automotive, industrial, and consumer markets.

The MJD31CT4-A belongs to ST's automotive-qualified power transistor product line, engineered specifically for robust, high-current switching in harsh-environment 12 V/24 V systems-including engine control, lighting, and actuator interfaces.

FAQ

Is MJD31CT4-A pin-compatible with MJD31C?

Yes-MJD31CT4-A shares identical DPAK (TO-252) pinout (B-C-E) and mechanical footprint with MJD31C. However, MJD31CT4-A adds AEC-Q101 qualification and improved thermal resistance (8.3 vs. 9.0 °C/W), making it a drop-in upgrade for automotive applications requiring qualification.

What is the maximum allowable case temperature for continuous 3 A operation?

At 3 A I_C, power dissipation is ~3.6 W (using V_CE(sat) = 1.2 V). With R_thJC = 8.3 °C/W, ΔT = 29.9 °C above case temperature. To stay within 150 °C max T_J, T_C must not exceed 120.1 °C-achievable with adequate PCB copper area or heatsink attachment.

Can MJD31CT4-A be used in avalanche mode?

No-the datasheet does not specify avalanche energy rating (E_AS) or ruggedness testing. It is rated for V_CEO(sus) = 100 V under sustaining conditions but lacks documented avalanche capability; external clamping (e.g., TVS diode) is required for inductive load flyback protection.

Does the exposed tab require electrical isolation from the heatsink?

Yes-the tab is electrically connected to the collector (pin 2). If the heatsink is grounded, the collector must be isolated using insulating thermal pads or mica washers rated for ≥100 V dielectric strength to prevent short-circuit failure.

MJD31CT4-A Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

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):: 50µA

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

Power - Max:: 15 W

Frequency - Transition:: -

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DPAK

MJD31CT4-A FAQ

1.How can I place an order for MJD31CT4-A through Aetrix?

Please submit a Request for Quotation (RFQ) for MJD31CT4-A 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 MJD31CT4-A reliable?

The price and inventory of MJD31CT4-A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MJD31CT4-A is usually 5 days.

3.What payment methods are accepted for MJD31CT4-A?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MJD31CT4-A transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MJD31CT4-A?

MJD31CT4-A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MJD31CT4-A 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 MJD31CT4-A?

For technical support, including MJD31CT4-A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MJD31CT4-A requirements.

6.How does Aetrix verify that MJD31CT4-A is sourced from the original manufacturer or authorized distributors?

All MJD31CT4-A 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 MJD31CT4-A meets industry standards.

7.What is the process for return or replacement of MJD31CT4-A?

All MJD31CT4-A units undergo pre-shipment inspection (PSI). If there is an issue with MJD31CT4-A, 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 MJD31CT4-A part is unused and in its original packaging.

Return procedure for MJD31CT4-A:

1.Submit a request within 90 days.

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

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