TIP120 – Darlington NPN Transistor

8 January 2019 - 0 Comments

TIP120 Transistor

TIP120 Pinout

The TIP120 is a NPN Darlington Power Transistor. It can switch loads upto 60V with a peak current of 8A and continuous current of 5A. This makes it suitable for medium and high power electronics like controlling motors, solenoids or high power LEDs.

Pin Configuration

Pin Number	Pin Name	Description
1	Base	Controls the biasing of transistor, Used to turn ON or OFF the transistor
2	Collector	Current flows in through collector, normally connected to load
3	Emitter	Current Drains out through emitter, normally connected to ground

Features

NPN Medium-power Darlington Transistor
High DC Current Gain (hFE), typically 1000
Continuous Collector current (IC) is 5A
Collector-Emitter voltage (VCE) is 60V
Collector-Base voltage (VCB) is 60V
Emitter Base Voltage (VBE) is 5V
Base Current(IB) is 120mA
Peak load current is 8A
Available in To-220 Package

Note: Complete Technical Details can be found at the TIP120 datasheet given at the end of this page.

TIP120 Equivalent Transistors

TIP127 (PNP), 2N5306, 2N6532, 2SD1415, 2SD2495, BDT63, BDW2, KSB601, KSD560, MJF6388

Complementary PNP Transistors

TIP125, TIP126, TIP127 (PNP)

Same Family Transistors

TIP121, TIP122 (NPN)

Alternative NPN Transistors

BC549, BC636, 2N2222A, BC547, 2N2219, 2N4401, 2N3904, BD139

TIP120 Transistor Overview

The TIP122 is a Darlington pair NPN transistor. It functions like a normal NPN transistor, but since it has a Darlington pair inside it has good collector current rating of about 5A and a gain of about 1000. It can also withstand about 60V across its collector- Emitter hence can be used to drive heavy loads. If you need more voltage then you can check other transistor in the same family lit the TIP122. The Darlington pair inside this transistor is shown clearly as its internal circuit schematic below

TIP120 darlington pair

As you can see, there are two transistors inside this TO-220 package in which the emitter of first transistor is connected with the base of second transistor and the collector of both transistors are connected together to form a Darlington pair. This increases the current gain and current rating of this transistor.

Where to use TIP120 Transistor

TIP120 transistor is known for its high current gain (hfe = 1000) and high collector current (IC =5A) hence it is normally used to control loads with high current or in applications where high amplification is required. This transistor has a low Base-Emitter Voltage of only 5V hence can be easily controlled by a Logic device like microcontrollers. Although care has to be taken to check if the logic device can source upto 120mA.

So, if you looking for a transistor that could be easily controlled by a Logic device to switch high power loads or to amplify high current then this Transistor might be an ideal choice for your application.