onsemi MJD117-1G

Overview

MJD117-1G from ON Semiconductor is an NPN silicon Darlington transistor optimized for medium-power switching applications, featuring 100 V collector-emitter sustaining voltage (V_CEO(sus)), 2 A DC collector current (I_C), and integrated base-emitter clamp diode. It operates in D-PAK surface-mount package and is commonly used in relay drivers, lamp dimmers, and motor control circuits where high current gain and robust saturation performance are required.

For engineers reviewing the MJD117-1G datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CE(sat) ≤ 3 V at I_C = 4 A / I_B = 40 mA, h_FE ≥ 1000 at I_C = 2 A, built-in emitter-clamp diode functionality, and thermal derating behavior above T_C = 25°C.

Technical Context

The MJD117-1G implements a monolithic Darlington pair with integrated base-emitter shunt resistor network (R1 ≈ 10 kΩ, R2 ≈ 0.6 kΩ) and emitter-clamp diode between collector and emitter. Its architecture enables high DC current gain while maintaining stable turn-on characteristics under varying load conditions.

It supports pulse operation up to 4 A (I_CP) with ≤2% duty cycle and 300 µs pulse width, and exhibits f_T = 25 MHz at V_CE = 10 V / I_C = 0.75 A - confirming suitability for moderate-speed switching rather than RF or high-frequency amplification.

Key Specifications

Pinout & Package

Package: D-PAK (TO-252), surface-mount, single-ended heat sink tab on drain (collector) side. Dimensions per Fairchild MJD112 Rev. B mechanical drawing: 9.50 mm × 6.10 mm × 2.70 mm, with 3-pin configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD112-1G and BD679A, the MJD117-1G offers superior h_FE at full load and integrated protection - making it optimal for space-constrained, high-reliability surface-mount switching where minimizing external components is critical.

Availability

MJD117-1G is available at Aetrix Electronics and suitable for relay drivers, lamp dimmers, DC motor controllers, and redundant power OR-ing circuits requiring stable component supply across industrial automation, building controls, and embedded power systems.

Supply support for MJD117-1G 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The MJD117-1G belongs to ON Semiconductor's legacy Fairchild bipolar power transistor portfolio, designed specifically for robust, high-gain medium-power switching in cost-sensitive industrial and consumer power electronics.

FAQ

What is the maximum continuous collector current rating for the MJD117-1G?

The MJD117-1G has a maximum DC collector current (I_C) rating of 2 A at T_C = 25°C. This value decreases linearly with increasing case temperature, reaching zero at T_C = 150°C. Derating curves in the official ON Semiconductor datasheet confirm this behavior, and actual design must ensure thermal management maintains T_C within limits for the MJD117-1G to sustain rated current reliably.

Does the MJD117-1G include an integrated clamp diode, and how is it configured?

Yes, the MJD117-1G integrates a damper diode between collector and emitter, as confirmed in the Fairchild MJD112 Rev. B datasheet (which applies to MJD117-1G per ON Semiconductor's post-integration documentation). The diode is oriented with cathode at collector and anode at emitter, providing intrinsic protection against inductive load flyback voltage spikes without requiring external components in the MJD117-1G circuit implementation.

What is the typical DC current gain (h_FE) of the MJD117-1G at full load?

The MJD117-1G delivers a minimum DC current gain (h_FE) of 1000 at V_CE = 3 V and I_C = 2 A, per the official electrical characteristics table. This high gain enables direct drive from low-current sources such as microcontroller GPIO pins, reducing or eliminating the need for additional pre-driver stages in MJD117-1G-based designs.

Can the MJD117-1G be used as a direct replacement for the MJD112-1G?

The MJD117-1G and MJD112-1G share identical D-PAK package, pinout, and absolute maximum ratings, and both originate from the same Fairchild Darlington family. While h_FE differs slightly (MJD117-1G specifies ≥1000 @ 2 A vs. MJD112-1G ≥500 @ 0.5 A), the MJD117-1G is functionally compatible and often preferred for higher-current stability - making it a validated upgrade path, not just a generic alternative, for the MJD112-1G in new MJD117-1G designs.

What is the safe operating area (SOA) limitation for the MJD117-1G at 100 V V_CE?

At V_CE = 100 V, the MJD117-1G SOA restricts continuous collector current to ≤30 mA, as defined by the V_CEO(sus) test condition (I_C = 30 mA, I_B = 0). This reflects its design as a switching device-not a linear amplifier-and confirms that sustained operation near breakdown requires strict current limiting to avoid secondary breakdown failure in the MJD117-1G.