onsemi 2N6426_D26Z

Overview

2N6426_D26Z from Fairchild Semiconductor is an NPN Darlington transistor in TO-92 package, designed for high-current-gain switching and amplification up to 1.2 A continuous collector current, with V_CEO = 40 V and h_FE ≥ 20,000 at I_C = 10 mA. It serves as a low-input-drive power switch in relay drivers, lamp controllers, and small-motor interfaces.

For engineers reviewing the 2N6426_D26Z datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed h_FE > 20k at 500 mA, V_CE(sat) ≤ 1.5 V under I_B = 0.5 mA drive, thermal resistance R_θJA = 200 °C/W, and TO-92 mechanical compatibility with standard through-hole PCB layouts.

Technical Context

The 2N6426_D26Z implements a monolithic NPN Darlington pair architecture, delivering ultra-high DC current gain (h_FE up to 300,000) while maintaining V_BE(sat) = 2.0 V at I_C = 500 mA - enabling direct microcontroller GPIO drive without external base resistors in many cases.

Its OFF-state leakage is tightly specified: ICEO ≤ 1.0 µA at V_CE = 25 V and ICBO ≤ 50 nA at V_CB = 30 V, supporting stable operation in battery-powered or high-impedance bias networks. The device operates across –55°C to +150°C junction temperature range and is rated for 625 mW total dissipation at 25°C.

Key Specifications

Pinout & Package

2N6426_D26Z is supplied in TO-92 plastic package (standard straight lead configuration, no lead clip), with flat side facing viewer and leads downward. Pin identification follows JEDEC TO-92 outline: Emitter (left), Base (center), Collector (right) when viewed from flat side with leads pointing down.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA14 and ULN2003A, the 2N6426_D26Z offers highest single-device h_FE among TO-92 Darlington transistors, making it optimal for ultra-low-drive applications where space and component count are constrained but channel count is low.

Availability

2N6426_D26Z is available at Aetrix Electronics and suitable for relay drivers, lamp controllers, solenoid actuators, and small DC motor starters requiring stable component supply and long-lifecycle support.

Supply support for 2N6426_D26Z 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 devices before its acquisition by ON Semiconductor in 2016.

The 2N6426_D26Z belongs to Fairchild's legacy discrete power transistor family, engineered for robust, low-cost, high-gain switching in industrial control, appliance, and instrumentation systems.

FAQ

What is the maximum continuous collector current rating for the 2N6426_D26Z?

The 2N6426_D26Z has a maximum continuous collector current (I_C) rating of 1.2 A at T_A = 25°C. Derating applies above 25°C at 5.0 mW/°C, and actual usable current depends on PCB copper area, ambient temperature, and thermal interface. At 70°C ambient, the practical continuous current drops to approximately 950 mA to maintain T_J ≤ 150°C.

Does the 2N6426_D26Z have integrated base resistors or protection features?

No, the 2N6426_D26Z is a bare NPN Darlington transistor without internal base resistors, clamp diodes, or ESD protection. External components - such as series base resistor for current limiting and parallel flyback diode for inductive loads - must be added per application requirements. This design preserves flexibility for custom biasing and thermal optimization.

What is the pin configuration of the 2N6426_D26Z in TO-92 package?

When viewing the 2N6426_D26Z from the flat side with leads pointing downward, the pin order is Emitter (left), Base (center), Collector (right). This matches JEDEC TO-92 standard orientation. The D26Z suffix confirms tape-and-reel packaging with emitter-first feed direction and adhesive tape on top side, per Fairchild's TO-92 TNR specification.

Can the 2N6426_D26Z replace the MPSA14 in existing designs?

The 2N6426_D26Z can functionally replace the MPSA14 in most low-frequency switching applications due to identical TO-92 package, pinout, and voltage ratings. However, its higher minimum h_FE (20,000 vs. 10,000) may cause faster turn-on and increased sensitivity to stray base current - verify stability in high-impedance bias networks or elevated temperature conditions before substitution.

Is the 2N6426_D26Z suitable for PWM motor speed control?

Yes, the 2N6426_D26Z supports PWM-based motor control at frequencies up to ~5 kHz, provided duty cycle and average current remain within I_C = 1.2 A and P_D = 625 mW limits. Its Darlington structure introduces slower switching than MOSFETs, so rise/fall times exceed 1 µs - acceptable for fan or pump control but not for high-efficiency brushless commutation.