onsemi TIP120TU

Overview

TIP120TU from onsemi is an NPN epitaxial Darlington transistor in TO-220 package, rated for 60 V V_CEO, 5 A DC collector current, and 65 W case power dissipation at 25°C. It delivers high DC current gain (h_FE ≥ 1000 at I_C = 0.5–3 A), low saturation voltage (V_CE(sat) = 2.0 V @ I_C = 3 A, I_B = 12 mA), and operates up to 150°C junction temperature-used in medium-power linear/switching applications such as motor drivers and relay interfaces.

For engineers reviewing the TIP120TU datasheet, pinout, applications, or equivalent options, key selection criteria include V_CEO/V_CBO rating, h_FE consistency across load range, thermal derating behavior, safe operating area (SOA) limits, and compatibility with base-drive circuitry requiring ≤120 mA I_B.

Technical Context

The TIP120TU integrates two cascaded NPN transistors in a monolithic Darlington configuration with internal base-emitter resistors (R1 ≈ 8 kΩ, R2 ≈ 0.12 kΩ), enabling high current amplification while simplifying external bias design. Its structure supports both linear amplification and saturated switching modes, with specified V_CE(sat) and V_BE(on) validated under pulsed and DC conditions.

Thermal performance is defined by case-to-ambient (2 W) and case-to-heatsink (65 W) dissipation limits, requiring mechanical mounting to heatsinks for sustained >1 A operation. Electrical characteristics-including ICEO ≤ 0.5 mA at V_CE = 30 V and Cob = 200 pF at V_CB = 10 V-are measured per JEDEC test conditions with pulse width ≤ 300 μs and duty cycle ≤ 2%.

Key Specifications

Pinout & Package

Package: TO-220 3L (Single Gauge), through-hole, vertical mounting with metal tab electrically connected to collector. Requires insulated mounting hardware if collector is not at ground potential.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BD679A and TIP122TU, the TIP120TU provides optimal balance of voltage rating, current capacity, and thermal performance in TO-220 for 24–48 V industrial switching-offering higher power handling than BD679A and better cost-efficiency than TIP122TU where 60 V suffices.

Availability

TIP120TU is available at Aetrix Electronics and suitable for DC motor control, relay driving, lamp dimming, and linear power regulation requiring stable component supply across prototyping, pilot production, and long-lifecycle industrial deployments.

Supply support for TIP120TU 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, and consumer markets.

The TIP120TU belongs to onsemi's legacy bipolar power transistor product line, engineered for ruggedized medium-power switching and linear applications where reliability, thermal stability, and ease of drive are critical.

FAQ

What is the maximum continuous collector current for the TIP120TU?

The TIP120TU supports 5 A DC collector current when operated within its thermal limits-specifically, with case temperature maintained at 25°C using adequate heatsinking. At higher case temperatures, current must be reduced per the linear derating curve (65 W → 0 W at 150°C). Pulse current up to 8 A is allowed under strict conditions (pulse width ≤ 300 μs, duty cycle ≤ 2%). The TIP120TU datasheet specifies these limits in Absolute Maximum Ratings and Thermal Characteristics sections.

Is the TIP120TU pin-compatible with other TIP12x series devices?

Yes-the TIP120TU shares identical TO-220 3L package and pinout (Base, Collector, Emitter) with TIP121TU and TIP122TU. All three have the same physical layout and terminal assignments, enabling direct substitution in existing PCBs when voltage rating requirements align. However, V_CEO differs (60 V for TIP120TU, 80 V for TIP121TU, 100 V for TIP122TU), so electrical validation is required before interchange.

Does the TIP120TU require a base current limiting resistor?

Yes-a series base resistor is mandatory to limit I_B to ≤120 mA DC and prevent damage. For example, driving from a 5 V MCU GPIO with target I_C = 3 A (requiring ~3 mA base drive due to h_FE ≥ 1000) needs ~1.5 kΩ resistor. The TIP120TU's internal R1/R2 resistors do not eliminate this requirement-they only provide turn-off bias and reduce leakage, not base current control.

Can the TIP120TU be used in linear regulator applications?

Yes-the TIP120TU is qualified for linear operation with specified V_CE(sat), h_FE, and SOA curves. Its 65 W case power rating and thermal derating profile support use as a series pass element in adjustable regulators delivering up to 5 A, provided heatsink design maintains T_C ≤ 25°C at full load. The TIP120TU's low V_BE(on) (2.5 V) also simplifies error-amplifier interface design.

What is the emitter-base breakdown voltage of the TIP120TU?

The TIP120TU has a guaranteed V_EBO (emitter-base breakdown voltage) of 5 V minimum, tested with collector open. This limits allowable reverse bias on the base-emitter junction-critical when driving inductive loads or using active pull-down circuits. Exceeding 5 V in reverse can cause junction breakdown and permanent degradation. The TIP120TU's internal R2 resistor (~0.12 kΩ) helps mitigate this risk but does not raise the absolute rating.