STMicroelectronics TIP120

Overview

TIP120 from STMicroelectronics is an NPN silicon Darlington power transistor in TO-220 package, designed for high-gain switching and linear amplification with 5 A continuous collector current, 60 V collector-emitter sustaining voltage (V_CEO(sus)), and low 2 V saturation voltage at 3 A/12 mA drive. It integrates monolithic base-island Darlington structure with built-in 7 kΩ and 70 Ω bias resistors, enabling direct TTL/CMOS logic interface in motor drivers, lamp controllers, and relay interfaces.

For engineers reviewing the TIP120 datasheet, TIP120 pinout, TIP120 application, or TIP120 equivalent, key selection criteria include verified DC current gain ≥1000 at 0.5–3 A, thermal resistance R_thJC = 1.92 °C/W, safe operating area up to 5 A/60 V DC, and compatibility with non-inductive resistive loads under pulsed conditions ≤300 μs.

Technical Context

The TIP120 implements a monolithic planar Darlington pair with integrated base-emitter resistors (R1 = 7 kΩ, R2 = 70 Ω), eliminating external bias components while maintaining precise turn-on control. Its "base island" layout ensures stable h_FE across temperature (−40 °C to 125 °C) and minimizes leakage (I_CEO ≤ 0.5 mA at V_CE = 30 V).

It operates in both linear and saturated switching modes, with V_CE(sat) ≤ 2 V at I_C = 3 A/I_B = 12 mA and V_BE(on) ≈ 2.5 V at I_C = 3 A/V_CE = 3 V. Switching performance is characterized by rise/fall times under 100 ns and storage time <1000 ns into resistive loads at 30 V supply.

Key Specifications

Pinout & Package

Package: TO-220 type H (tab-connected collector), with isolated mounting hole and standardized mechanical dimensions per DS0854 Rev 5 Table 4.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSD12 and TIP122, the TIP120 offers the lowest V_CE(sat) among standard Darlington transistors in its class and optimal thermal efficiency for 24 V/5 A switching-making it preferred for space-constrained, thermally demanding linear and PWM applications.

Availability

TIP120 is available at Aetrix Electronics and suitable for DC motor control, lamp driving, relay interfacing, and industrial PLC output stages requiring stable component supply, long-term manufacturability, and traceable sourcing.

Supply support for TIP120 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, analog, microcontrollers, and automotive-grade ICs with strong manufacturing control and environmental compliance programs.

The TIP120 belongs to ST's STPOWER discrete portfolio, engineered specifically for robust, high-current switching in industrial automation, appliance control, and embedded power systems where reliability under thermal and electrical stress is critical.

FAQ

What is the maximum safe continuous collector current for TIP120?

The TIP120 is rated for 5 A continuous collector current (I_C) at case temperature T_C ≤ 25°C. Derating is required above this temperature per Figure 2: at T_C = 75°C, maximum I_C drops to ~3.2 A. Operation beyond 5 A requires pulsed conditions (I_CM = 8 A, ≤300 μs, ≤2% duty cycle) and strict thermal management.

Does TIP120 require an external flyback diode when driving inductive loads?

Yes-TIP120 does not integrate a flyback diode. When switching relays, solenoids, or DC motors, an external fast-recovery diode (e.g., 1N4007 or MUR120) must be connected cathode-to-collector, anode-to-emitter to clamp inductive kickback and prevent junction breakdown. This is explicitly required per application note AN4112 and Figure 17 test circuit.

Can TIP120 be used in linear amplifier mode, and what is its typical h_FE in that region?

Yes-TIP120 is specified for linear operation with h_FE ≥1000 at I_C = 0.5 A and 3 A (V_CE = 3 V, T_J = 25°C). In analog amplifier use, it delivers stable gain across −40 °C to 125 °C (Figure 3), but thermal runaway mitigation (emitter degeneration resistor, heatsinking) is mandatory due to positive temperature coefficient of V_BE.

Is the metal tab of TIP120 electrically isolated from other pins?

No-the metal tab is internally connected to Pin 2 (collector) and is not insulated. When mounted to a heatsink, the collector becomes electrically tied to the heatsink potential. Electrical isolation requires insulating hardware (mica washer, silicone pad) and shoulder washers, especially in grounded-heatsink configurations to avoid short circuits.