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MJD122T4G

ONMJD122T4G

onsemi
Bipolar (BJT) Transistor NPN - Darlington 100 V 8 A 4MHz 1.75 W Surface Mount DPAK
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Overview

The MJD122T4G is a high-gain NPN Darlington power transistor in a surface-mount DPAK package, designed for general-purpose amplifier and low-speed switching applications. It features a high DC current gain of 2500 typical at 4.0 A and is rated for a collector-emitter voltage of 100 V. Its monolithic construction includes built-in base-emitter shunt resistors to improve switching performance and thermal stability.

Why Choose This Part

This device offers a high current-handling capability of 8 A in a compact DPAK footprint, making it ideal for space-constrained power designs. The Darlington configuration provides an extremely high gain, significantly reducing the base drive current required from a microcontroller. Additionally, it is designed as a surface-mount replacement for the popular TIP122 series, facilitating easy migration from through-hole to SMD production.

Applications

Relay and Solenoid Drivers
The high current gain allows direct interfacing with low-power logic to drive high-current inductive loads.
DC Motor Control
Suitable for driving small DC motors in pulse-width modulation (PWM) or simple on/off configurations up to 8 A.
Stepping Motor Drivers
Utilized in the output stages of unipolar stepper motor controllers due to its high voltage and current ratings.
LED Array Dimming
Used as a low-side switch for controlling high-power LED strings in industrial lighting applications.

Key Specifications

Power - Max 1.75 W
Mounting Type Surface Mount
Package / Case TO-252-3, DPAK (2 Leads + Tab), SC-63
Transistor Type NPN - Darlington
Operating Temperature -65degC ~ 150degC (TJ)
Frequency - Transition 4MHz
Supplier Device Package DPAK
Vce Saturation (Max) @ Ib, Ic 4V @ 80mA, 8A
Current - Collector (Ic) (Max) 8 A
Current - Collector Cutoff (Max) 10uA
DC Current Gain (hFE) (Min) @ Ic, Vce 1000 @ 4A, 4V
Voltage - Collector Emitter Breakdown (Max) 100 V

Getting Started

When designing with the MJD122T4G, ensure adequate PCB copper pour area connected to the collector tab to manage the 1.75 W power dissipation. Use a base resistor to limit the input current from your MCU and include a flyback diode when driving inductive loads to prevent voltage spikes from exceeding the 100 V rating. For thermal modeling, refer to the DPAK thermal resistance specifications to verify junction temperatures remain below 150 degrees Celsius.