TIP122 Darlington NPN Transistor - (Pack of 5)

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Length

10.67 mm (0.42 in)

Width

5.33 mm (0.21 in)

Height

4.57 mm (0.18 in)

Conclusion

The TIP122 Darlington NPN transistor is a high-performance, high-reliability component that is ideal for a wide range of applications requiring high current and voltage switching. Its compact TO-220 package and built-in base-emitter diode make it an excellent choice for designers and hobbyists alike.

Pin Configuration

TIP122 Darlington NPN Transistor Documentation
Pinout and Connection Guide
The TIP122 is a Darlington NPN transistor array, packaged in a TO-220 package. It consists of five transistors per package, making it a convenient and cost-effective solution for various electronic projects. Here's a detailed explanation of each pin and how to connect them:
Pin 1: Base (B)
Function: Input pin, controls the transistor's operation
Description: Apply a small voltage to this pin to control the flow of current between the collector and emitter
Connection:
+ Connect to a microcontroller's digital output or an external voltage source (e.g., a resistor divider network)
+ Typically requires a current-limiting resistor (e.g., 1 k to 10 k) to prevent excessive base current
Pin 2: Collector (C)
Function: High-current output pin
Description: Carries the load current, which is amplified from the base current
Connection:
+ Connect to the positive supply voltage (VCC) or the load (e.g., a relay, LED, or motor)
+ Ensure the collector current is within the transistor's rating (up to 5 A for the TIP122)
Pin 3: Emitter (E)
Function: Low-current output pin
Description: Completes the circuit when the transistor is in saturation
Connection:
+ Connect to ground (GND) or a negative supply voltage
+ Typically requires a current-limiting resistor (e.g., 1 k to 10 k) to prevent excessive emitter current
Important Connection Notes:
Always connect the base-emitter junction in a way that prevents excessive current flow, which can damage the transistor.
Use a current-limiting resistor in series with the base pin to prevent overheating and ensure stable operation.
Ensure the total power dissipation (PD) of the transistor does not exceed its rating (up to 65 W for the TIP122).
When driving inductive loads (e.g., relays, motors), use a flyback diode to protect the transistor from back-EMF.
Example Connection Diagram:
Here's a basic connection diagram to illustrate the pin connections:
Vin (5V) R1 (1 k) Base (B)
Vin (5V) Load (e.g., Relay) Collector (C)
GND Emitter (E)
R2 (1 k) Base (B) GND (optional, for base-emitter limiting)
In this example, Vin is the input voltage, R1 is the current-limiting resistor, and R2 is an optional base-emitter resistor.
Remember to consult the datasheet and relevant application notes for specific usage guidelines and precautions when working with the TIP122 Darlington NPN transistor array.

Code Examples

TIP122 Darlington NPN Transistor Documentation

Overview

The TIP122 Darlington NPN transistor is a high-power, high-gain transistor designed for high-current applications. It consists of a pair of NPN transistors connected in a Darlington configuration, which provides a high current gain and high input impedance. This transistor is commonly used in power switching, motor control, and relay driver applications.

Pinout

The TIP122 Darlington NPN transistor has a TO-220 package with three pins:

| Pin | Function |
| --- | --- |
| Base (B) | Control input |
| Collector (C) | Output |
| Emitter (E) | Ground |

Features

High current gain (hFE): 1000-2500
 High input impedance
 Low saturation voltage (VCE(sat)): 2V
 High power dissipation: 65W
 Operating temperature range: -55C to 150C

Example 1: Using the TIP122 as a Relay Driver

In this example, the TIP122 is used to drive a 12V relay. The relay is connected to a microcontroller's digital output pin.

Circuit Diagram

```
  +---------------+
  |              |
  |  Microcontroller  |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  TIP122 (Q1)  |
  |  Base (B)    |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  Relay (RLY1) |
  |  Coil        |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  Diode (D1)   |
  |  (1N4007)    |
  |              |
  +---------------+
           |
           |
           v
  GND
```

Code Example (Arduino)
```c
const int relayPin = 2;  // Digital output pin connected to TIP122 base

void setup() {
  pinMode(relayPin, OUTPUT);
}

void loop() {
  digitalWrite(relayPin, HIGH);  // Turn on the relay
  delay(1000);
  digitalWrite(relayPin, LOW);  // Turn off the relay
  delay(1000);
}
```

Example 2: Using the TIP122 as a Motor Driver

In this example, the TIP122 is used to drive a 12V DC motor.

Circuit Diagram

```
  +---------------+
  |              |
  |  Microcontroller  |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  TIP122 (Q1)  |
  |  Base (B)    |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  Motor (M1)  |
  |  12V DC      |
  |              |
  +---------------+
           |
           |
           v
  +---------------+
  |              |
  |  Diode (D1)   |
  |  (1N4007)    |
  |              |
  +---------------+
           |
           |
           v
  GND
```

Code Example (Arduino)
```c
const int motorPin = 3;  // Digital output pin connected to TIP122 base

void setup() {
  pinMode(motorPin, OUTPUT);
}

void loop() {
  digitalWrite(motorPin, HIGH);  // Turn on the motor
  delay(2000);
  digitalWrite(motorPin, LOW);  // Turn off the motor
  delay(2000);
}
```
Important Notes

When using the TIP122, ensure that the base current is limited to prevent overheating and damage to the transistor.
 Use a suitable heat sink for high-power applications to prevent overheating.
 Follow proper PCB design and layout practices to minimize electromagnetic interference and ensure reliable operation.