onsemi TIP42BG

Overview

TIP42BG from onsemi is a PNP silicon power transistor in TO-220 package, rated for 80 V_CEO, 6 A continuous collector current, and 65 W power dissipation at T_C = 25°C, designed for linear amplification and hard-switching applications in industrial power supplies and motor control circuits.

For engineers reviewing the TIP42BG datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO = 80 V, I_C = 6 A, h_FE ≥ 15 (at I_C = 3.0 A), V_CE(sat) ≤ 1.5 V (at I_C = 6 A, I_B = 600 mA), and thermal resistance R_JC = 1.67 °C/W - all critical for thermal management and saturation performance in high-current DC switching stages.

Technical Context

The TIP42BG operates as a medium-power PNP bipolar junction transistor with complementary pairing to TIP41BG (NPN). Its safe operating area (SOA) is defined up to 150°C junction temperature, with secondary breakdown limits validated for single-pulse operation at 1 ms and 5 ms durations under specified test conditions.

It features a DC current gain (h_FE) of 15–75 across 0.3–3.0 A collector current range, V_BE(on) ≤ 2.0 V at I_C = 6 A, and f_T = 3.0 MHz - enabling use in audio-frequency amplifiers and low-to-moderate-speed switching circuits where gain stability and voltage headroom are prioritized over RF performance.

Key Specifications

Pinout & Package

Package: TO-220 (Case 221A, Style 1), 3-terminal plastic power package with metal tab electrically connected to collector (pins 2 and 4). Mounting hole allows mechanical attachment to heatsink with electrical isolation required if collector is not at ground potential.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD42G and BD912, the TIP42BG delivers superior thermal performance in through-hole mounting configurations, supports legacy TO-220 heatsink footprints, and maintains proven reliability in industrial motor and power supply designs where mechanical robustness and serviceability are prioritized over miniaturization.

Availability

TIP42BG is available at Aetrix Electronics and suitable for industrial motor drivers, linear power supplies, audio amplifier output stages, and relay/solenoid control circuits requiring stable component supply and long-term manufacturability assurance.

Supply support for TIP42BG 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 management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The TIP42BG belongs to onsemi's legacy silicon power transistor family engineered for cost-sensitive, high-reliability linear and switching applications in industrial controls, power conversion, and audio systems - emphasizing ruggedness, thermal stability, and ease of integration.

FAQ

What is the maximum collector-emitter voltage rating for TIP42BG?

The TIP42BG has a maximum collector-emitter sustaining voltage (V_CEO(sus)) of 80 Vdc, tested at I_C = 30 mA and I_B = 0. This rating defines the absolute upper limit for voltage applied between collector and emitter while ensuring device integrity under open-base conditions. Exceeding this value risks avalanche breakdown and permanent damage to the TIP42BG.

Does TIP42BG require a heatsink in typical applications?

Yes, the TIP42BG requires a heatsink in any application where power dissipation exceeds ~2 W at ambient temperature. With R_JA = 57 °C/W and a maximum junction temperature of 150°C, even 1 W of dissipation raises junction temperature by 57°C above ambient. For its rated 65 W at T_C = 25°C, a properly mounted heatsink maintaining case temperature near 25°C is essential - making heatsink selection mandatory for all but very low-duty-cycle or low-current uses of the TIP42BG.

What is the DC current gain (h_FE) range for TIP42BG at 3.0 A collector current?

At I_C = 3.0 A and V_CE = 4.0 Vdc, the TIP42BG exhibits a DC current gain (h_FE) ranging from 15 to 75. This wide spread reflects process variation and necessitates design margin in base drive circuitry - for example, sizing base resistors to deliver ≥600 mA to guarantee saturation even at the minimum h_FE of 15. The TIP42BG datasheet specifies this range explicitly in the Electrical Characteristics table under "ON CHARACTERISTICS".

Is TIP42BG pin-compatible with other TIP42x variants like TIP42CG?

No, the TIP42BG is not pin-incompatible with TIP42CG in terms of electrical function or package - both use identical TO-220 (Style 1) pinout with Base-Pin 1, Collector-Pins 2&4, and Emitter-Pin 3. However, they differ in maximum voltage ratings: TIP42BG is rated for 80 V_CEO, while TIP42CG is rated for 100 V_CEO. Substituting TIP42CG for TIP42BG introduces no layout change but may incur unnecessary cost and slightly different gain/switching characteristics; substituting TIP42BG for TIP42CG risks overvoltage failure if circuit stresses exceed 80 V.

What does the 'G' suffix indicate in TIP42BG?

The 'G' suffix in TIP42BG denotes a Pb-free (lead-free) and RoHS-compliant package per onsemi's standard marking convention. It confirms that the device uses environmentally compliant materials and plating, with no lead in the die attach, bond wires, or external terminations. This designation appears in the marking diagram and ordering information sections of the official TIP42BG datasheet and is consistent across the TIP41x/TIP42x family - distinguishing it from obsolete non-Pb-free versions discontinued prior to 2024.