onsemi 2N6040

Overview

2N6040 from onsemi is a PNP silicon Darlington transistor in TO-220 package, rated for 60 V_CEO(sus) (min), 8 A continuous collector current, and 75 W power dissipation at T_C = 25°C. It delivers high DC current gain (h_FE = 1000 min @ I_C = 4.0 A), low V_CE(sat) ≤ 2.0 V @ I_C = 4.0 A / I_B = 16 mA, and features monolithic construction with built-in base-emitter shunt resistors - used in medium-power linear amplifiers and low-speed switching circuits such as relay drivers and lamp controls.

For engineers reviewing the 2N6040 datasheet, pinout, applications, or equivalent options, this page provides verified electrical specifications, thermal derating behavior, safe operating area limits, junction-to-case thermal resistance (1.67°C/W), and complementary NPN alternatives - all confirmed from onsemi's official Rev. 11 datasheet (2026).

Technical Context

The 2N6040 operates as a high-gain PNP Darlington pair with integrated base-emitter shunt resistor, enabling simplified biasing and improved turn-off speed over standard bipolar transistors. Its sustaining voltage rating (V_CEO(sus) = 60 Vdc min at I_C = 100 mA) and second-breakdown-limited SOA support robust operation in inductive load switching up to 75 W at case temperatures ≤25°C.

Thermal design is constrained by R_θJC = 1.67°C/W and R_θJA = 57°C/W; power derating begins above 25°C at 0.60 W/°C. The device exhibits h_FE ≥1000 at I_C = 4.0 A and maintains usable gain down to I_C = 0.1 A, with V_BE(sat) ≤ 4.5 V and V_BE(on) ≤ 2.8 V under rated conditions.

Key Specifications

Pinout & Package

2N6040 is housed in a TO-220 (Case 221A, Style 1) plastic package with three leads: Collector (tab), Base, and Emitter. The metal tab is electrically connected to the collector and must be isolated from chassis ground unless circuit design requires collector-to-heatsink connection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 2N6042 and MJD127, the 2N6040 offers optimal cost-performance balance for 24–40 VDC switching at through-hole assembly scale, with superior thermal resistance and proven reliability in legacy industrial control designs.

Availability

2N6040 is available at Aetrix Electronics and suitable for relay driver circuits, lamp dimming controls, motor start assist modules, and linear DC power supply regulators requiring stable component supply and long-term industrial lifecycle support.

Supply support for 2N6040 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 manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The 2N6040 belongs to onsemi's legacy plastic medium-power complementary silicon transistor family, designed specifically for general-purpose amplifier and low-speed switching applications where high current gain and ruggedness outweigh RF or high-frequency requirements.

FAQ

What is the maximum continuous collector current rating for the 2N6040?

The 2N6040 has a maximum continuous collector current (I_C) rating of 8.0 Adc at case temperature T_C = 25°C. This rating decreases linearly above 25°C at 0.60 W/°C per the derating curve in Figure 1 of the onsemi datasheet. At T_C = 100°C, the usable I_C drops to approximately 3.5 A to maintain safe junction temperature.

Does the 2N6040 have built-in base-emitter resistors?

Yes, the 2N6040 features monolithic construction with a built-in base-emitter shunt resistor. This internal resistor improves turn-off speed and eliminates the need for an external pull-down component in most switching applications, simplifying driver design and enhancing reliability in relay and lamp control circuits using the 2N6040.

What is the thermal resistance from junction to case for the 2N6040?

The thermal resistance from junction to case (R_θJC) for the 2N6040 is 1.67°C/W, as specified in the Thermal Characteristics table of the onsemi datasheet. This value is critical for calculating junction temperature rise under load and must be used with measured case temperature to ensure operation remains within the –65°C to +150°C junction temperature range.

Can the 2N6040 be used as a direct replacement for the 2N6042 in a 60 V circuit?

No - while both are PNP Darlington transistors in TO-220 packages, the 2N6042 is rated for V_CEO(sus) = 100 Vdc (min), whereas the 2N6040 is rated for 60 Vdc (min). Using the 2N6040 in place of the 2N6042 in a 60 V nominal circuit risks exceeding its sustaining voltage limit during transients, making it unsuitable as a drop-in replacement without circuit revalidation.

What packaging and compliance standards apply to the 2N6040G variant?

The 2N6040G is the Pb-free, RoHS-compliant version of the 2N6040, packaged in TO-220 (Case 221A) with UL 94 V-0 rated epoxy at 0.125 in thickness. It ships in rails of 50 units and meets onsemi's environmental compliance requirements including JESD22-A114 (HBM > 8 kV) and JESD22-A115 (MM > 400 V), as documented in the official 2N6040/D datasheet Rev. 11.