onsemi MJE700STU

Overview

MJE700STU from Fairchild Semiconductor is a PNP epitaxial silicon Darlington transistor in TO-126 package, rated for -60 V V_CEO, -4 A I_C, and 40 W P_C at T_C=25°C, with built-in base-emitter resistors (R1 ≈ 10 kΩ, R2 ≈ 0.6 kΩ), used in high-gain linear amplification and medium-power switching applications such as relay drivers and power supply error amplifiers.

For engineers reviewing the MJE700STU datasheet, pinout, applications, or equivalent options, key selection considerations include its Darlington configuration, integrated bias resistors, -60 V/–4 A rating, thermal derating curve, and complementary pairing with MJE800-series devices.

Technical Context

The MJE700STU implements a monolithic Darlington pair with integrated base-emitter resistors, enabling simplified biasing and improved DC current gain stability. Its structure delivers h_FE ≥ 750 at I_C = –1.5 A and V_CE = –3 V, while maintaining V_CE(sat) ≤ –2.5 V under same conditions.

Designed for linear and switching operation up to 150°C junction temperature, it features low leakage (I_CEO ≤ –100 µA at V_CE = –60 V), robust safe operating area (SOA) up to 5 ms pulse width, and thermal resistance R_θJC ≈ 0.625°C/W derived from 40 W P_C and 25°C T_C rating.

Key Specifications

Pinout & Package

Package: TO-126 - plastic molded, through-hole, 3-lead power package with metal tab for heatsink mounting; dimensions per Fairchild Rev. A1 (16.10 × 13.06 × 4.2 mm typical).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP Darlington transistor applications.

Compared with BD679A and MJE702STU, the MJE700STU offers optimized integration for cost-sensitive, space-constrained designs where –60 V rating suffices and built-in resistors reduce bill-of-materials overhead.

Availability

MJE700STU is available at Aetrix Electronics and suitable for relay driver circuits, linear power supply error amplifiers, DCC model railroad decoders, and DC motor speed controllers requiring stable component supply and long-term industrial availability.

Supply support for MJE700STU 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The MJE700STU belongs to Fairchild's legacy bipolar power transistor family designed for medium-power linear and switching applications in industrial controls, power supplies, and automotive subsystems.

FAQ

What is the maximum junction temperature for the MJE700STU?

The MJE700STU has a maximum junction temperature (T_J) of 150°C, as specified in its Absolute Maximum Ratings table. This rating governs thermal design margins and heatsink sizing. Operation beyond 150°C risks permanent degradation. The MJE700STU must be mounted on an appropriate heatsink to maintain T_J within limit under full 40 W dissipation. Derating curves in the datasheet show allowable power reduction above 25°C case temperature.

Does the MJE700STU have built-in base resistors?

Yes, the MJE700STU includes two monolithically integrated base-emitter resistors: R1 ≈ 10 kΩ and R2 ≈ 0.6 kΩ, as shown in its equivalent circuit diagram. These resistors enable self-biasing and eliminate the need for external base drive components. This feature simplifies circuit design and improves reliability in relay drivers and error amplifiers where the MJE700STU is commonly deployed.

Is the MJE700STU pin-compatible with the MJE702STU?

Yes, the MJE700STU and MJE702STU share identical TO-126 package, pinout (Emitter–Collector–Base), and internal resistor network. Their only electrical difference is V_CEO: –60 V for MJE700STU versus –80 V for MJE702STU. No PCB changes are required when substituting MJE702STU for higher voltage margin, though the MJE700STU remains optimal where –60 V suffices.

What is the DC current gain (hFE) of the MJE700STU at different operating points?

The MJE700STU specifies h_FE ≥ 750 at V_CE = –3 V and I_C = –1.5 A, and also ≥ 750 at I_C = –2 A for MJE701/703 variants. At full rated I_C = –4 A, h_FE drops to ≥ 100. This graded gain behavior reflects Darlington saturation effects and must be considered in high-current linear designs. The MJE700STU maintains usable gain across its operational range, supporting both switching and amplification roles.

Can the MJE700STU be used in H-bridge motor control?

Yes, the MJE700STU is suitable as the high-side PNP switch in complementary H-bridge configurations when paired with NPN counterparts like MJE800-series transistors. Its –60 V V_CEO, –4 A I_C, and matched SOA support bidirectional 12–24 V DC motor control. Careful attention to dead-time and base drive sequencing is required to avoid shoot-through. The MJE700STU's built-in resistors simplify gate drive but do not replace active level-shifting in high-frequency PWM.