onsemi TIP42

Overview

TIP42CTU from onsemi is a PNP epitaxial silicon power transistor in TO-220 package, rated for -100 V V_CEO, -6 A DC collector current, 65 W case power dissipation at 25°C, and 3.0 MHz f_T; used in medium-power linear and switching applications such as voltage regulators and audio output stages.

For engineers reviewing the TIP42CTU datasheet, pinout, applications, or equivalent options, key selection factors include its -100 V V_CEO rating, -6 A I_C capability, TO-220 thermal performance, and complementary pairing with TIP41 series devices.

Technical Context

This PNP bipolar junction transistor operates in linear amplification or saturated switching modes, with h_FE ranging from 30 (at -0.3 A) to 75 (min) and 15 (at -3 A), and exhibits V_CE(sat) ≤ -1.5 V at -6 A / -600 mA drive. Its safe operating area supports pulsed currents up to -10 A with defined derating above 25°C case temperature.

The device features a single-gauge TO-220 package with electrically isolated tab, enabling direct heatsink mounting without insulating hardware. Thermal resistance R_θJC is implied by 65 W P_C at T_C = 25°C, and it complies with JEDEC TO-220 AB mechanical dimensions.

Key Specifications

Pinout & Package

Package: TO-220 3L (Single Gauge), with electrically isolated metal tab (pin 2, Collector) and standard JEDEC AB outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TIP42CTU, MJD42C trades thermal capability for SMT compatibility, while BD912 offers higher current but reduced voltage margin-both require layout and thermal redesign, and neither is pin-compatible.

Availability

TIP42CTU is available at Aetrix Electronics and suitable for audio amplifiers, linear voltage regulators, motor drivers, and power supply switching stages requiring stable component supply and long-term industrial availability.

Supply support for TIP42CTU 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, and cloud infrastructure markets.

The TIP42CTU belongs to onsemi's legacy discrete power transistor family, designed specifically for cost-sensitive, medium-power linear and switching applications where reliability, thermal robustness, and JEDEC-standard packaging are essential.

FAQ

What is the maximum collector-emitter voltage rating for TIP42CTU?

The TIP42CTU has a maximum collector-emitter sustaining voltage (V_CEO(sus)) of -100 V under specified test conditions (I_C = -30 mA, I_B = 0). This rating defines the upper limit of reverse bias the device can withstand before avalanche breakdown occurs. Exceeding -100 V risks irreversible damage. The TIP42CTU datasheet confirms this value applies specifically to the TIP42C variant, which includes the TIP42CTU ordering option.

Is TIP42CTU pin-compatible with other TIP42 variants like TIP42C or TIP42?

Yes, TIP42CTU shares identical pinout (Base–Collector–Emitter), package (TO-220 3L), and electrical specifications with the TIP42C variant. The "TU" suffix denotes tape-and-reel or rail packaging per onsemi's ordering convention, not functional or mechanical differentiation. TIP42CTU is functionally and physically interchangeable with TIP42C in all circuit implementations.

What is the typical DC current gain (h_FE) of TIP42CTU at common operating points?

The TIP42CTU exhibits h_FE = 30–75 depending on bias conditions: minimum 30 at V_CE = -4 V and I_C = -0.3 A, and minimum 15 at V_CE = -4 V and I_C = -3 A. These values are confirmed in the onsemi TIP42C/D datasheet and reflect the device's gain compression under higher current loads-critical for designing stable bias networks in linear amplifier stages using TIP42CTU.

Can TIP42CTU be used as a direct replacement for TIP42 in existing designs?

No-TIP42CTU corresponds to the TIP42C specification (-100 V V_CEO), whereas the base TIP42 is rated for only -40 V V_CEO. Substituting TIP42CTU for TIP42 may be acceptable if the circuit never exposes the transistor to >-40 V, but doing so forfeits the safety margin inherent in the -40 V part. Always verify voltage stress margins before interchanging TIP42CTU and TIP42 in legacy designs.

What thermal derating applies to TIP42CTU above 25°C case temperature?

TIP42CTU's 65 W power dissipation rating applies only at T_C = 25°C. Above that, power must be linearly derated at 0.52 W/°C (based on 65 W ÷ (150°C − 25°C)), reaching zero at the maximum junction temperature of 150°C. This derating curve is documented in Figure 4 of the onsemi TIP42C/D datasheet and directly governs heatsink sizing and ambient temperature limits for reliable TIP42CTU operation.