Hello everyone! I hope you will be absolutely fine and having fun. Today, I am going to give the Introduction to ULN2003. It is basically a relay driver IC and it is a darlington array having high voltages and high currents as well. It is made up of seven open collector darlington pairs having common emitter which shows ULN2003 has a capability of handling seven different relays at a time. You should also have a look at Relay Interfacing with Microcontroller using ULN2003A. ULN2003A is exactly the same as ULN2003with some small differences which are not of much importance.
A single darlington pair consists of two bipolar transistors and it operates on the current range of 500mA to 600mA. ULN200X is a well known series of IC’s. ULN2003 is also the part of this series. ULN2003 operates on 5V and TTL (Transistor Transistor Logic) and CMOS (Complementary Metal Oxide Semi Conductor). Its pin configuration is designed so that the input pins are at the left side of the IC whereas the the output pins of it are on right side in front of the corresponding input pin. This IC has a very wide range of applications. They are commonly used as relay drivers in order to drive different kinds of loads. ULN2003A can also be used to drive different motors (e.g. DC Motors or Stepper Motors) with Microcontrollers (like Arduino, PIC Microcontroller or 8051 Microcontroller etc.) . Some of the other applications of ULN2003 include logic buffers, lamp drivers, line drivers, LED display, motor driver circuits etc.
Introduction to ULN2003
ULN2003 is a relay driver IC consisting of a darlington array. It is made up of seven open collector darlington pairs with common emitter. Moreover, ULN2003A has a capability of handling seven different Relays simultaneously. A single darlington pair consists of two bipolar transistors and operates in the range of 500mA to 600mA current.
- Here’s the link to ULN2003 datasheet, must read it once.
- I have also given the link of a reliable source, from where you can buy this IC.
1. ULN2003 Pinout
- ULN2003 has 16 pins in total out of which there are:
- 7 Input pins (Pin # 1 to Pin # 7)
- 7 Output pins (Pin # 10 to Pin # 16)
- 1 Ground pin (Pin # 8)
- 1 COM pin (Pin # 9)
- The pin diagram for ULN2003 is shown in the figure below.
Its pin division on the basis of functions associated with them is shown in above figure. Further description will be given in this tutorial later. In short the pins can be divided into four different categories i.e. input pins, output pins, ground pin and common pin. These pins along with their positions are shown below.
2. ULN2003 Pin Description
- The functions associated with each pin of ULN2003 along with the pin names are shown in the table given below.
3. Internal Circuit Diagram
- Internal circuit diagram of ULN 2003 having different resistors and diodes is shown in the figure below.
4. Logic Diagram
- Internally, ULN2003A is made of hybrid combination of logic gates and diodes.
- The logic diagram for ULN2003 is shown in the figure below.
5. Key Features
There are a lot of keys features associated with the relay driver ULN2003. A few of which are given below.
- 500mA of rated collector.
- High output voltage of around 50V.
- Relay driver applications.
- Output clamp diodes.
- Compatible input with popular logic types.
- Some of the key features are also given in the table below for the better understanding about the working conditions of ULN2003.
The relay circuit driver ULN2003 has a wide range of applications in real life. Some of the major applications associated with ULN-2003 are given below.
- Logic buffers.
- Line drivers.
- Relay drivers (for driving different loads).
- Lamp drivers.
- LED display drivers (display devices).
- Motor (stepper and DC brushed motor) drivers.
6. ULN2003 Proteus Simulation
- I have made simulation in Proteus ISIS for LED control using ULN2003.
- The screenshot of the simulation is shown in the figure below.
- As you can see in the above figure that I have connected Logic State at all inputs of ULN 2003 and have connected Leds at outputs.
- So, now when I make the Logic State HIGH then the respective LED will also go ON.
- The running form of the above simulation is shown in the figure below.
- If you change the state of the logic state from 0 to 1, corresponding LED will be turned ON as shown in the above figure.
- You can download the Proteus simulation here by clicking on the button below.
- Just download .rar file, extract it and enjoy the simulation.
- Here’s the video in which I have shown how to use ULN2003 in Proteus: