onsemi MJD340RLG

Overview

MJD340RLG from ON Semiconductor is a high-voltage NPN epitaxial silicon power transistor in D-PAK package, rated for 300 V V_CEO, 0.5 A DC collector current, and 15 W collector dissipation at T_C = 25°C. It serves as a switching or linear amplifier in high-voltage industrial power supplies and relay drivers.

For engineers reviewing the MJD340RLG datasheet, pinout, applications, or equivalent options, key selection considerations include its 300 V blocking capability, 30–240 h_FE gain range at 50 mA, 150°C junction temperature rating, and D-PAK thermal performance for surface-mount high-voltage switching.

Technical Context

The MJD340RLG operates as a single NPN bipolar junction transistor with epitaxial base construction optimized for high-voltage breakdown and rugged safe operating area (SOA). Its V_CEO(sus) = 300 V under I_C = 1 mA, I_B = 0 confirms sustaining voltage capability critical for snubberless flyback and inductive load switching.

Thermal design relies on case-mounted heat sinking: 15 W P_C at T_C = 25°C drops to 1.56 W at T_A = 25°C, indicating strong dependence on PCB copper area and thermal vias. The device exhibits V_CE(sat) ≤ 1.5 V at I_C = 0.5 A, I_B = 50 mA per typical curves.

Key Specifications

Pinout & Package

D-PAK (TO-252) surface-mount package with gull-wing leads; thermally enhanced die attach to exposed drain pad (Pin 2), requiring soldered thermal pad for rated power dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD340RLG, MJD350RLG serves only complementary roles and cannot replace it functionally, while STN3PF30 offers MOSFET advantages in speed and drive simplicity but trades off gain, saturation voltage, and thermal robustness in linear operation.

Availability

MJD340RLG is available at Aetrix Electronics and suitable for industrial relay drivers, AC-DC power supply switches, and DC motor control applications requiring stable component supply and long-term manufacturability.

Supply support for MJD340RLG 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

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 MJD340RLG belongs to ON Semiconductor's high-voltage discrete transistor product line, engineered for rugged, cost-effective switching in industrial power conversion and control systems where reliability under voltage stress is critical.

FAQ

What is the maximum continuous collector current rating for MJD340RLG?

The MJD340RLG has a maximum DC collector current (I_C) rating of 0.5 A at T_C = 25°C. This rating assumes adequate heatsinking; actual usable current decreases significantly with rising case temperature and must be derated per the power derating curve in the datasheet. For reliable long-term operation, design should target ≤0.4 A under typical board-level thermal conditions.

Does MJD340RLG support pulse operation beyond its DC current rating?

Yes, the MJD340RLG supports pulsed collector current up to 0.75 A under specified test conditions (PW ≤ 300 µs, duty cycle ≤ 2%). This capability is validated by its Safe Operating Area (SOA) curve and enables short-duration surge handling in relay driving or motor commutation. Pulse operation must respect second-breakdown limits and thermal accumulation across consecutive pulses.

What package type does MJD340RLG use, and how is thermal management addressed?

MJD340RLG uses the D-PAK (TO-252) surface-mount package with an exposed collector tab. Thermal management requires soldering the tab to a large copper area (≥250 mm², 2-oz) with multiple thermal vias to internal ground planes. The 15 W power dissipation rating applies only when T_C is maintained at 25°C - ambient-limited operation at T_A = 25°C yields just 1.56 W.

Is MJD340RLG suitable for linear amplifier applications?

Yes, the MJD340RLG can be used in linear amplifier configurations due to its wide h_FE range (30–240), low leakage (I_CEO ≤ 0.1 mA), and stable SOA. However, linear operation demands strict thermal control and bias stability design, especially near its 150°C junction limit. It is more commonly applied in saturated switching roles where gain variation has less impact.

What is the base-emitter breakdown voltage specification for MJD340RLG?

The MJD340RLG has a maximum emitter-base voltage (V_EBO) rating of 3 V. Exceeding this voltage risks irreversible damage to the base-emitter junction. In practical circuits, base drive must be clamped or limited - especially during inductive turn-off events - using Zener diodes or active clamp networks to prevent reverse breakdown.