TIP122 Transistor | Datasheet, Circuit Diagram, NPN Darlington | Pinout & Equivalent STMicroelectronics

TIP122 NPN transistor 5A 100V

TIP122 Pinout

The TIP122 is a Darlington NPN power transistor housed in a TO-220 package. It features an internal pair of transistors with resistors and a base-emitter protection diode, making it ideal for high-gain switching and amplification. Below is the detailed pin configuration:

The TIP122 integrates internal resistors (R1 = 7kΩ and R2 = 70Ω) and a diode for safe and efficient Darlington operation. It is commonly used in motor drivers, relay drivers, and power control circuits due to its high gain and ease of use.

TIP122 Equivalent

This table is a replacement table for the equivalent type TIP122. They are both NPN type transistors, and their main role in circuits is power amplification, circuit switching, and so on.

Picture	Name	Makers	Maximum Power (W)	Maximum Current (A)	Maximum Voltage (V)	Package Type
	TIP122	STMicroelectronics	65	5	100	TO-220
	MJ11015	Motorola	120	15	80	TO-3
	2N3055	Motorola	115	6	40	TO-3
	2N4922G	ON Semiconductor	30	3	60	TO-220
	MJE3055TG	ON Semiconductor	75	10	60	TO-220
	BD139	STMicroelectronics	35	1.5	80	TO-126

Note:

The best substitute in this table is MJE3055TG, its parameters are similar to TIP122, when replacing TIP122, just make sure that the actual circuit voltage does not exceed 60 V. When using BD139 as a substitute, there are many more constraints, you need to pay attention to the actual circuit power, current, and voltage do not exceed 35W, 1.5A, and 80 V. When using the other models in the table as a substitute, you also need to pay attention to the actual conditions in the circuit. When using the other models in the table as alternatives, it is also necessary to pay attention to the actual conditions in the circuit.

TIP122 Circuit Diagram

TIP122 Transistor Pinout

TIP122 Specific Parameters:

Package type: TO-220;.

Transistor type: NPN type Darlington transistor;

Maximum DC gain: 1000 (theoretically can amplify current up to 1000 times);

Continuous collector current is: 5A;

Maximum collector-emitter withstand voltage value: 60V;.

Maximum collector base voltage: 60V.

Peak load current: 8A (not sustainable, longer duration will burn out the components);

Operating temperature: -65 to +150 ℃ (the design of the circuit should be careful to avoid prolonged exposure to extremely low or high temperatures)

Principle of operation and internal structure:

As shown in the right half of the tip122 Picture, tip122 consists of two NPN transistors connected to each other (the emitter of the first transistor is connected to the base of the second transistor), so that the amplification of the current can be realised, if the first transistor amplification is A, the second amplification is B then the amplification power of the Darlington tube is A*B.

Tip122 enlarged experimental diagram

From the figure, we can see that the input current is 42.2ma, the output current is 3.09A, and the amplification is 3.09/0.0422=73.2 times. Why not to the actual 1000 times? Because the energy in the circuit can not be generated out of thin air, so there needs to be a power supply, theoretically speaking, as long as the power supply is large enough then the current gain can reach 1000.