onsemi MJE344G

Overview

MJE344G from onsemi is a plastic NPN silicon medium-power transistor rated for 200 V_CEO, 500 mA continuous collector current, and 20 W total power dissipation at T_C = 25°C, with f_T ≥ 15 MHz - designed for medium-voltage converter and extended-range amplifier applications.

For engineers reviewing the MJE344G datasheet, pinout, applications, or equivalent options, key selection considerations include V_CEO/V_CB = 200 V, h_FE = 30–300 at I_C = 50 mA, V_CE(sat) ≤ 1.0 V, thermal resistance R_θJC = 6.25°C/W, and TO-225 package compatibility with medium-power switching and linear amplification roles.

Technical Context

The MJE344G operates as a general-purpose NPN bipolar junction transistor optimized for medium-voltage, medium-current switching and analog amplification. Its safe operating area (SOA) is defined by thermal limits (T_J ≤ 150°C) and second-breakdown constraints, with pulse operation up to 10% duty cycle permitted at T_J(pk) ≤ 150°C.

Electrical behavior is characterized by DC current gain h_FE spanning 30–300 at I_C = 50 mA/V_CE = 10 V, V_BE(on) ≤ 1.0 V, and output capacitance C_ob ≤ 15 pF at V_CB = 20 V - supporting stable high-frequency gain and low capacitive loading in driver and amplifier stages.

Key Specifications

Pinout & Package

Package: TO-225 (Case 77-09, Style 1), plastic through-hole package with metal tab (pins 2 and 4 both connected to collector, backside tab electrically tied to collector).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJE344G, MJE340G offers identical form factor but half the voltage rating, limiting use to sub-100 V systems; BD237 delivers higher current in a different package but sacrifices voltage headroom and high-frequency response - neither is pin-compatible, and PCB layout changes are required for either alternative.

Availability

MJE344G is available at Aetrix Electronics and suitable for switch-mode power supply drivers, audio output stages, DC motor control circuits, and linear voltage regulator pass elements requiring stable component supply across industrial and embedded design cycles.

Supply support for MJE344G 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 focused on energy-efficient electronics, with leadership in power management, analog, sensors, and discrete devices.

The MJE344G belongs to onsemi's legacy medium-power bipolar transistor family, engineered for reliability in industrial power conversion, audio amplification, and control circuitry where robust 200 V operation and thermal stability are critical.

FAQ

What is the maximum collector-emitter voltage rating for the MJE344G?

The MJE344G has a maximum collector-emitter sustaining voltage V_CEO(sus) of 200 Vdc at I_C = 1.0 mAdc and I_B = 0. This rating is validated per the onsemi datasheet Rev. 4 (December 2013) and defines the absolute upper limit for safe DC or repetitive peak operation without avalanche breakdown. Exceeding this voltage risks permanent device failure.

Does the MJE344G have a built-in heatsink tab, and how is it electrically connected?

Yes, the MJE344G in TO-225 package features a metal backside tab that serves as a mechanical heatsink interface and is electrically connected to the collector (pins 2 and 4). This requires electrical isolation from the mounting surface unless the collector node is referenced to chassis ground. The tab improves thermal transfer with R_θJC = 6.25°C/W.

What is the typical DC current gain (h_FE) range for the MJE344G, and under what conditions is it specified?

The MJE344G exhibits h_FE between 30 and 300, measured at I_C = 50 mAdc and V_CE = 10 Vdc per the official onsemi datasheet. This wide spread reflects process variation and necessitates circuit-level design margin - e.g., using emitter resistors or feedback - especially in linear applications where gain stability affects performance.

Can the MJE344G be used in switching applications above 1 MHz?

The MJE344G has a minimum f_T of 15 MHz, indicating usable small-signal current gain up to that frequency. However, its switching speed is limited by storage time and minority-carrier lifetime; practical hard-switching use is recommended below 500 kHz. For >1 MHz operation, consider RF-optimized transistors with shorter t_s and lower C_ob, as the MJE344G's 15 pF Cob and inherent BJT dynamics constrain high-frequency efficiency.

Is the MJE344G RoHS compliant, and what does the "G" suffix signify?

Yes, the MJE344G is RoHS compliant and Pb-free, as confirmed in the onsemi datasheet. The "G" suffix explicitly denotes the Pb-free package variant, consistent with onsemi's marking convention and compliance documentation. No lead-based solder or terminations are used, and the device meets EU Directive 2011/65/EU requirements.