onsemi MJF47

Overview

MJF47G from onsemi is an NPN silicon high-voltage power transistor in a TO-220 Fullpak isolated package, rated for 250 V_CEO(sus), 1 A continuous collector current, and 28.4 W at T_C = 25°C. It serves as a switching driver in line-operated audio output amplifiers and off-line switching power supplies where electrical isolation between the mounting surface and heatsink is mandatory.

For engineers reviewing the MJF47G datasheet, pinout, applications, or equivalent options, key selection criteria include its 3500 V_RMS UL-recognized isolation rating, 4.4 °C/W junction-to-case thermal resistance, and verified suitability for isolated-switching topologies requiring no external insulating washers.

Technical Context

The MJF47G is a ruggedized bipolar junction transistor optimized for high-voltage switching with sustained breakdown capability (V_CEO(sus) = 250 V) and low saturation voltage (V_CE(sat) ≤ 1 V at I_C = 1 A, I_B = 0.2 A). Its fully isolated TO-220 Fullpak package eliminates need for mica washers or silicone pads during heatsink mounting.

Thermal performance is defined by R_JC = 4.4 °C/W (measured at insulated base surface), and safe operating area (SOA) curves confirm robustness under pulsed conditions up to 150 °C peak junction temperature. Switching times are characterized at V_CC = 200 V with I_C/I_B = 5, supporting reliable operation in hard-switched converters.

Key Specifications

Pinout & Package

Package: TO-220 Fullpak (Case 221D-03), fully isolated plastic package with electrically insulated mounting surface. Mounting torque must not exceed 10 in·lbs to preserve isolation integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TIP47G and MJF44G, the MJF47G uniquely combines 250 V blocking, 3500 V_RMS isolation, and TO-220 Fullpak packaging-enabling single-component compliance with IEC 62368-1 reinforced insulation requirements in compact AC-powered systems.

Availability

MJF47G is available at Aetrix Electronics and suitable for line-operated audio amplifiers, off-line switching power supplies, and industrial motor control circuits requiring stable component supply across multi-year production cycles.

Supply support for MJF47G 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, high-reliability power, analog, sensor, and connectivity solutions.

The MJF47G belongs to onsemi's high-voltage discrete power transistor family, engineered specifically for cost-sensitive, safety-critical AC-powered equipment where electrical isolation and thermal reliability are non-negotiable.

FAQ

What is the maximum mounting torque specification for the MJF47G?

The MJF47G must be mounted with a screw torque no greater than 10 in·lbs. Exceeding this value risks cracking the plastic package around the mounting hole, which compromises the 3500 V_RMS isolation rating. onsemi validates thermal performance and isolation integrity only within this torque limit, and recommends using a compression washer to maintain consistent pressure across temperature cycles. The MJF47G datasheet explicitly warns against exceeding 10 in·lbs under any mounting condition.

Does the MJF47G require external insulating hardware when mounted to a heatsink?

No, the MJF47G does not require external insulating hardware. Its TO-220 Fullpak package features a fully isolated mounting surface certified to 3500 V_RMS per UL File #E69369. This eliminates the need for mica washers, silicone pads, or insulating sleeves-reducing assembly steps and thermal interface resistance. The MJF47G achieves this isolation through internal molding and dielectric construction, not external components.

What is the safe operating area (SOA) limitation for the MJF47G at 100 V_CE?

At V_CE = 100 V, the MJF47G's maximum allowable collector current is 0.3 A for DC operation, as defined by the thermal limit curve in Figure 7 of the datasheet. For pulsed operation (≤10% duty cycle), the SOA extends to 1 A at 100 V_CE, constrained by secondary breakdown. These limits assume T_C = 25°C and peak junction temperature ≤150°C. The MJF47G's SOA is validated with single-pulse testing, not repetitive stress.

Is the MJF47G pin-compatible with the TIP47 series?

Yes, the MJF47G is pin-compatible with the TIP47 series in TO-220 package configuration (Style 2: Pin 1 = Base, Pin 2 = Collector, Pin 3 = Emitter). However, it is not a direct functional replacement due to its integrated isolation and higher V_CEO(sus) rating. While PCB layout remains unchanged, the MJF47G enables elimination of insulating hardware and supports higher bus voltages-making it a functional upgrade, not just a drop-in swap.

What is the typical f_T (transition frequency) of the MJF47G?

The MJF47G has a minimum f_T of 10 MHz, measured at I_C = 0.2 A, V_CE = 10 V, and f = 2 MHz. This transition frequency reflects its usable bandwidth for switching applications up to approximately 1–2 MHz, though practical hard-switching operation is typically limited to ≤100 kHz due to SOA and thermal constraints. The f_T value is specified in the Electrical Characteristics table and confirmed in the Typical Characteristics section of the MJF47G datasheet.