1. Uln2803 Stepper Motor Driver Circuit
2. Uln2803 Stepper Motor Driver Circuit Diagram
3. Uln2803 Stepper Motor Driver Circuit Breaker
4. Uln2803 Stepper Motor Driver Circuit Board

We looked at the L293D in Lesson 9. The ULN2803 is a very useful chip. Whereas the L293D effectively has four outputs whose polarity can be reversed, the ULN2803 has eight outputs that amplify the weak signals from the raspberry Pi GPIO pins allowing them to switch much higher currents. The inputs can be driven by 3.3V or 5V logic. Fits nicely in any breadboard or perfboard. Please Note: Your chip may have a part marking of ULQ2803A, this is the extended temperature range version of the ULN2803A, so it can run from -40 to 105 °C. It is otherwise identical in pin out, usage, voltage and current capabilities. It is 5V DC unipolar stepper motor. We are also using a Module available with this motor which consist ULN2003 Stepper Motor Driver IC. ULN2003 is a Darlington pair array, which is useful to drive this motor, since PIC microcontroller couldn’t provide enough current to drive. ULN2003A is capable to drive 500mA of load with 600mA of peak current. In this lesson, you will learn how to control a stepper motor using your Raspberry Pi and the same L293D motor control chip that you used with the DC motor in Lesson 9. The Lesson will also show you how to use an alternative driver chip, the ULN2803.

Hey Guys! Hope you are doing well. I always take pleasure to keep you updated with valuable information related to information and technology. Today, I'll discuss the detailed Introduction to ULN2803 which is a relay driver that comes with a high-voltage and high-current Darlingtontransistor array. In order to obtain higher current capability, the Darlington pairs are connected in a parallel configuration.The component is incorporated with eight NPN Darlington pairs, featuring high-voltage outputs with common-cathode clamp diodes that are directly related to switching inductive loads. Each Darlington pair features a decent amount of collector-current rating i.e. around 500 mA.You must have a look at ULN2003 which is almost similar to this IC but comes with 16 pins and can handle 7 relays at a time.In this post, I'll cover each and everything related to this driver IC: its main features, pinout, working, and applications. Let's dive in.

Introduction to ULN2803

ULN2803 is a high-voltage and high-current Darlington transistor array and is mainly used as a relay driver with an ability to handle 8 relays at a time.It comes with a collector-emitter voltage around 50 V and input voltage residing at 30 V.

• Before we move further, we must know what is Darlington transistor? It is commonly known as Darlington pair which is nothing but a combination of two bipolar transistors featuring a compound design and is connected back to back where current amplified by the first transistor is again amplified by the second one.

This shape delivers a much higher current gain as compared to each transistor taken separately. It works on the simple amplification principle happening in the regular transistor where a small base is used to make the pair switch for higher switching currents.

• This Darlington transistor mainly operates at 5V and is based on TTL (Transistor-Transistor Logic) and CMOS (Complementary Metal Oxide Semi-Conductor).

The NPN transistors forming arrays are useful for both: interfacing between low logic level digital circuitry and achieving the higher current/voltage requirements in a wide range of applications including printer hammers, lamps, relays, consumer and industrial applications.

• The device shows open–collector outputs and freewheeling clamp diodes that turn out to be very handy for transient suppression.

ULN2803 Pinout

Following figure shows the pinout of ULN2803. It comes with 8 input pins and 8 output pins.

Pin Configuration

Pin number from 1 to 8 is a Channel 1 through 8 Darlington base input while pin number from 11 to 18 is Channel 1 through 8 Darlington base output. Similarly, 9 and 10 pins are ground and common cathode node (Vcc) respectively. It is important to note that common emitter is shared by all the channels.Following table shows the pin configuration of ULN2803.

ULN2803 Logic Diagram

Uln2803 Stepper Motor Driver Circuit

Following figure shows the logic diagram of ULN2803. It is a visual representation and arrangement of how the diodes are connected in the component.Following figure shows the schematic diagram of each Darlington pair.You can see how the resistors and diodes are connected with each other. And the amplified output of one resistor is further amplified by the second resistor, giving a whopping amount of current gain which is difficult for the individual diode to achieve if incorporated separately.

ULN2803 Absolute Maximum Ratings

Following figure shows the absolute maximum rating of this component.These are the stress ratings which if exceed from absolute maximum ratings, can damage the device at large, ultimately affecting the overall nature and performance of the project.

• Similarly, if these ratings are applied for the maximum period of time above normal operating conditions they can affect the reliability of the device.

Steps and measurements taken in the early stages of your project can save you from the atrocities of spending more in case the electronic circuit gets affected.

• It is preferred to check these ratings before placing the device in the circuit and make sure these ratings are quite in line and match exactly as defined by the manufacturer.

Applications

ULN2803 comes with a variety of advantages with a common application as a relay driver. Following are some major applications of this Darlington array.

• LED display
• Hammer Drivers
• Motor driver circuits like DC Motors or Stepper Motors
• IP Camera
• Lamp Drivers
• Stepper Motors
• Logic Buffers
• Line Drivers
• HVAC Valve and LED Dot Matrix

This is all for today. I hope you have found this read valuable. If you have any question, you can approach me in the comment section below. I'd love to help you the best way I can. Your feedback and suggestions are a valuable asset for us. Based on them, we develop our content strategy, so keep them coming. Thanks for reading the article.

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I am Syed Zain Nasir, the founder of The Engineering Projects (TEP).I am a programmer since 2009 before that I just search things, make small projects and now I am sharing my knowledge through this platform.I also work as a freelancer and did many projects related to programming and electrical circuitry. My Google Profile+

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Uln2803 Stepper Motor Driver Circuit Diagram

This tutorial of Robo India explains how to drive Stepper Motor Using ULN2803 with Arduino UNO.

1. Introduction

Stepper motors are like DC motors, which is used to move in steps. These motors have multiple coils that are organised in group which is known as phase. In this tutorial, we have explained how to interface Step Motor 28BYJ-48 with Arduino UNO using ULN2803.

Stepper motors fall somewhere in between a regular DC motor and a servo motor. Servo motors are usually limited to 0-180 degree rotation, while a stepper motor can rotate continously like dc motors. They have the advantage that they can be positioned accurately and you can control over the movement. The only drawback of step motor is, they are little bit harder to control than other motors and servo motors.

1.1 Stepper Motor Working:

There are two types of Stepper motors: Unipolar and Bipolar. The difference between the two types is the voltage levels.

A unipolar stepper motor only operates with positive voltage, so the high and low voltages applied to the electromagnetic coils would be something like 5V and 0V.

And a bipolar stepper motor has two polarities, positive and negative, so its high and low voltages would be something like 2.5V and -2.5V.

Uln2803 Stepper Motor Driver Circuit Breaker

Different types of Stepper Motors have different numbers of wires like 4,5,6,8. In bipolar stepper motors, there are arrangements of 4 wires. Central wire is not available

The stepper motor, which we have used has 5 wires, implying that it is to be run as a unipolar stepper motor. This 5th wire is to allow current on coils to flow in two directions

1.2 ULN2803 IC:

ULN2803 is a high current, high voltage IC, used to drive high power loads upto 500mA/50V such as relays, motors etc.

2. Hardware required

Uln2803 Stepper Motor Driver Circuit Board

S.No.	Item	Quantity
1	Arduino UNO	1
2	Breadboard	1
3	28BYJ-48 Stepper Motor	2
4	ULN2803 IC	7
5	Male to male Jumper	11

3. Connection:

Use the colors of the leads to identify them, not the position from which they emerge from the motor.

4. Programming:

5. Output

After uploading the above code, the stepper motor will start rotating continously.

There are many usage of stepper motors, which includes medical scanners, 3D printers, in cameras, auomated blinds and more.

If you have any query please write us at support@roboindia.com

Thanks and Regards
Content Development Team
Robo India
https://roboindia.com