onsemi 2N6426G

Overview

2N6426G from onsemi is an NPN silicon Darlington transistor in TO-92 package, rated for 40 V_CEO, 500 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 20,000–200,000 at I_C = 10–500 mA, with V_CE(sat) ≤ 1.2 V and V_BE(sat) ≤ 2.0 V, enabling high-sensitivity switching in low-power control circuits such as relay drivers and sensor interface stages.

For engineers reviewing the 2N6426G datasheet, pinout, applications, or equivalent options, this device is selected for low-input-current amplification tasks where high h_FE, low saturation voltage, and Pb-free TO-92 packaging are required - especially in discrete logic-level interface, solid-state relay emulation, and analog signal conditioning designs.

Technical Context

The 2N6426G implements a monolithic two-stage NPN Darlington configuration, delivering ultra-high DC current gain while maintaining defined saturation characteristics under controlled base drive. Its thermal resistance R_JA = 200°C/W and R_JC = 83.3°C/W support operation across −55°C to +150°C junction temperature range, with validated noise performance (NF ≤ 10 dB at 1 kHz, I_C = 1 mA) and small-signal h_fe ≥ 20,000 at 1 kHz.

Electrical behavior is characterized by tight breakdown limits: V_(BR)CEO = 40 V (I_C = 10 mA), V_(BR)CBO = 40 V (I_C = 100 μA), and V_(BR)EBO = 12 V (I_E = 10 μA), ensuring robust off-state isolation. Input capacitance C_ibo = 10–15 pF and output capacitance C_obo = 5.4–7.0 pF enable stable operation in low-frequency switching and linear amplification up to 100 MHz bandwidth.

Key Specifications

Pinout & Package

2N6426G is housed in a Pb-free TO-92 (Case 29-11) plastic package with straight or bent leads, featuring standardized three-terminal layout optimized for through-hole PCB assembly and manual prototyping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA13 and ULN2003A, the 2N6426G offers superior voltage rating and highest h_FE among TO-92 Darlington transistors, making it optimal for single-load, high-isolation, low-drive applications where discrete simplicity and legacy through-hole compatibility are prioritized.

Availability

2N6426G is available at Aetrix Electronics and suitable for relay drivers, sensor interfaces, thermal protection circuits, and LED current regulation requiring stable component supply and long-term obsolescence management.

Supply support for 2N6426G 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, medical, and IoT applications.

The 2N6426G belongs to onsemi's legacy discrete transistor portfolio, designed specifically for high-gain, low-input-current switching and amplification in cost-sensitive, reliability-critical applications where TO-92 form factor and Pb-free compliance are mandatory.

FAQ

What is the maximum collector-emitter voltage rating for the 2N6426G?

The 2N6426G has a guaranteed minimum collector-emitter breakdown voltage V_(BR)CEO of 40 V at I_C = 10 mA. This rating is confirmed in the official onsemi datasheet (Publication Order Number 2N6426/D, Rev. 3) and defines the absolute upper limit for safe DC operation. Exceeding 40 V risks avalanche conduction and permanent device failure. The 2N6426G must not be used in circuits where transient spikes or ripple could push V_CE beyond this value without clamping protection.

Does the 2N6426G have built-in base-emitter resistors or protection diodes?

No, the 2N6426G is a bare Darlington transistor with no internal base-emitter resistors, clamp diodes, or ESD protection structures. It consists solely of two monolithically integrated NPN transistors. External components - such as a base series resistor to limit drive current and a flyback diode across inductive loads - must be added per application requirements. This absence of integrated protection distinguishes the 2N6426G from driver ICs like the ULN2003A and confirms its role as a fundamental discrete building block.

What is the typical DC current gain (h_FE) of the 2N6426G at 100 mA collector current?

At I_C = 100 mA and V_CE = 5.0 V, the 2N6426G exhibits a minimum h_FE of 30,000 and a maximum of 300,000, with typical performance centered around 100,000–200,000. This specification is explicitly listed in the "ELECTRICAL CHARACTERISTICS" table of the onsemi 2N6426/D datasheet. Designers should use the minimum value (30,000) for worst-case base drive calculations to ensure reliable saturation of the 2N6426G across process and temperature variations.

Can the 2N6426G be used in linear amplifier configurations?

Yes, the 2N6426G supports linear operation with verified small-signal parameters: h_fe ≥ 20,000 at 1 kHz, |h_fe| ≥ 1.5 at 100 MHz, input impedance h_ie = 100–2000 kΩ, and noise figure ≤ 10 dB at 1 kHz. These values confirm suitability for low-frequency analog amplification, provided thermal design accommodates power dissipation and biasing avoids saturation/cutoff regions. However, its Darlington structure introduces higher V_BE (~1.5 V) and slower switching than single transistors, limiting high-fidelity audio use.

Is the 2N6426G pin-compatible with the 2N6427G?

Yes, the 2N6426G and 2N6427G share identical TO-92 package dimensions, pinout (Emitter-Base-Collector on pins 1-2-3), and terminal assignments. They differ only in DC current gain: the 2N6427G specifies h_FE = 10,000–140,000 across the same test conditions. Both devices are drop-in replacements in layout and wiring; selection depends solely on required minimum gain and application tolerance for h_FE variation. No PCB changes are needed when substituting between these two variants.