onsemi MJF6388

Overview

MJF6388 from onsemi is an NPN complementary power Darlington transistor in an electrically isolated TO-220 Fullpack package, rated for 100 V_CEO, 10 A continuous collector current, and 40 W total power dissipation at T_C = 25°C. It delivers high DC current gain (h_FE = 15000 min at I_C = 3 A), low V_CE(sat) (≤2.0 V at I_C = 3 A, I_B = 6 mA), and 4500 V_RMS isolation voltage - designed for high-reliability switching and amplification in thermally demanding industrial motor drives and isolated power supply control stages.

For engineers reviewing the MJF6388 datasheet, pinout, applications, or equivalent options, key selection considerations include its electrically isolated TO-220 Fullpack mechanical design, 4.0°C/W junction-to-case thermal resistance, UL recognition at 3500 V_RMS, and compatibility with heatsink mounting without isolating washers - critical for safety-compliant AC/DC converter primary-side switching and industrial relay driver circuits.

Technical Context

The MJF6388 integrates a Darlington pair with internal base-emitter resistor network (~8 kΩ) and emitter-follower output stage, enabling high-current drive with minimal base drive requirements. Its isolated package eliminates need for insulating hardware while maintaining 3.0 pF collector-to-heatsink capacitance and 200 pF output capacitance (C_ob) at 10 V.

Thermal performance is defined by R_JC = 4.0°C/W (measured at insulated bottom surface) and R_JA = 62.5°C/W, supporting operation from –65°C to +150°C. Switching behavior includes typical turn-on time t_s < 7 µs and fall time t_f < 3 µs at I_C/I_B = 250, with safe operating area limited by secondary breakdown and thermal constraints up to 100 V and 10 A.

Key Specifications

Pinout & Package

Package: TO-220 Fullpack (Case 221D, Style 2), electrically isolated plastic overmold with metal tab connected to collector. Mounting screw 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 NPN Darlington switching applications.

Compared with 2N6388 and TIP102, the MJF6388 provides certified electrical isolation, superior thermal performance (4.0°C/W vs ≥5.0°C/W), and guaranteed UL compliance - making it the only suitable choice for safety-regulated industrial power switching where direct heatsink mounting is required.

Availability

MJF6388 is available at Aetrix Electronics and suitable for industrial motor control, AC/DC power supply feedback, and heating element control requiring stable component supply across long-lifecycle embedded programs.

Supply support for MJF6388 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 specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MJF6388 belongs to onsemi's Complementary Power Darlingtons product line, engineered specifically for electrically isolated high-current switching in safety-critical industrial and power conversion systems.

FAQ

What is the maximum mounting torque for the MJF6388?

The maximum recommended mounting torque for the MJF6388 is 10 in·lbs. Exceeding this value risks cracking the plastic package around the mounting hole, which compromises electrical isolation and voids UL recognition. onsemi validates thermal performance and isolation integrity only within this torque range, using a 4-40 screw with compression washer. Always verify torque with calibrated tools during production assembly of MJF6388-based systems.

Does the MJF6388 require an external base resistor?

Yes, the MJF6388 requires an external base resistor to limit base current and ensure reliable saturation. With h_FE ≥15000 at I_C = 3 A, a typical base current of ~0.2 mA is needed - meaning a 15 kΩ resistor is appropriate for 3.3 V drive. The MJF6388 does not integrate base resistors; omitting the external resistor risks excessive base current, thermal runaway, and premature failure. Designers must calculate resistor value based on driver voltage, desired I_C, and worst-case h_FE across temperature for MJF6388 applications.

Can the MJF6388 be used in linear regulator applications?

Yes, the MJF6388 can operate in linear mode, but only within its Safe Operating Area (SOA) limits. At T_C = 25°C, the thermal limit allows 40 W dissipation, but secondary breakdown restricts simultaneous high V_CE and I_C - e.g., 50 V × 0.5 A is permissible, while 50 V × 2 A exceeds SOA. Linear use demands active heatsinking and derating above 25°C (0.31 W/°C). For MJF6388 linear regulator designs, always reference Figure 4 (SOA curve) and apply transient thermal analysis per Figure 5.

What is the significance of the "G" suffix in MJF6388G?

The "G" suffix in MJF6388G denotes a Pb-free (lead-free) version compliant with RoHS Directive 2011/65/EU. It indicates that the device uses matte tin plating on leads and halogen-free molding compound, meeting JEDEC J-STD-020 moisture sensitivity level (MSL) 1 requirements. All MJF6388G units shipped by Aetrix Electronics are Pb-free; legacy non-G variants are obsolete. The "G" does not affect electrical or thermal specifications - MJF6388G performs identically to earlier leaded versions except for environmental compliance.

How does the MJF6388 compare to the MJF6668 in complementary pair usage?

The MJF6388 (NPN) and MJF6668 (PNP) form a complementary Darlington pair with matched voltage ratings (100 V), current capability (10 A), and isolation performance (4500 V_RMS). Their h_FE curves track closely across temperature, and both share identical TO-220 Fullpack packaging and pinout (Base-Collector-Emitter). This symmetry enables balanced push-pull output stages in audio amplifiers and H-bridge motor drivers - but designers must account for V_BE(on) differences (MJF6388: 2.5 V typ; MJF6668: 2.8 V typ) when designing bias networks for MJF6388/MJF6668 dual configurations.