TheULN2003AN is a real workhorse when it comes to controlling powerful devices with microcontrollers or digital logic circuits. This versatile IC allows you to control relays, motors, LEDs, solenoids and other devices with simple logic signals.
In this comprehensive guide, we’ll cover the operation of the ULN2003AN, its pin configuration, internal structure, typical applications and how to integrate it into your next project. We’ll also show you how to find quality ULN2003AN controller ICs and support components online.
What is ULN2003AN?
TheULN2003AN is a 7-channel Darlington transistor chip. Each channel can drive up to 500 mA current and withstand voltages up to 50 V, making it ideal for connecting low-power microcontrollers such as Arduino or STM32 to high-power loads.
Each of the Darlington pairs can amplify lower input currents to drive higher output currents – and can be used as an electronic switch for high-voltage or inductive loads.
Looking for the ULN2003AN controller IC? Browse DRex Electronics’ full catalogue.
ULN2003AN pinout and features
The ULN2003AN is available in a 16-pin DIP package, which is easy to use on breadboards and PCBs.
Description of the pins:
- Pins 1-7 (IN1-IN7): logic level inputs (connected to the microcontroller).
- Pins 10-16 (OUT1-OUT7): open collector outputs (connected to load).
- Pin 8 (GND): ground
- Pin 9 (COM): common continuity diode (connected to power supply for inductive loads).
Internal structure
Each channel of the ULN2003AN consists of the following components:
- A pair of Darlington transistors to increase the current gain.
- Inverting diodes to prevent voltage spikes caused by inductive loads.
- Open collector output for connecting external voltages and devices.
This makes it ideal for connecting relays, motors, solenoids and stepper motors .
Main features
- 7-channel high-current Darlington driver
- Each channel can handle up to 500 mAcurrent
- Maximum output voltage: 50 V
- Built-in clamping diode to protect inductive loads
- TTL/CMOS compatible inputs
- Often used in stepper motors and relay modules.
- Power supply from a single 5 V logic source
General applications of the ULN2003AN
Relay controllers
Connects several relays via microcontroller or logic signals. Built-in diode protects the circuit from reversal.
⚙️ 2. Stepper motor control
Typically used with 28BYJ-48 stepper motors. Used in printers, scanners and robots.
- LED arrays and displays
Easily control high-power LEDs or entire LED arrays.
- Electromagnetic actuator
Controls electromagnetic locks or valves with low voltage control circuits.
- Industrial automation
Used for switching high-power loads in PLCs and embedded control systems.
Use of ULN2003AN in circuits
- Connect IN1-IN7 to the digital outputs of a microcontroller (e.g. Arduino, Raspberry Pi).
- Connect OUT1-OUT7 to the negative terminal of the load (motor, relay, etc.).
- Connect COM (pin 9) to the positive voltage of the load (e.g. 12 or 24 V).
- Connect GND (pin 8) to system earth .
Tip: Current limiting resistors must be used to control LEDs and a feedback diode must always be used to control external inductive loads, even if the ULN2003AN has a built-in feedback diode.
Comparison of ULN2003AN and ULN2803
Features ULN2003AN ULN2803A
Number of channels 7 8
TTL/CMOS input compatibility TTL/CMOS
Current per channel 500 mA 500 mA
Relays, stepper motors, LED drivers, solenoids, electromagnets
If you need more channels, consider the ULN2803A with 8 outputs.
Where to buy ULN2003AN and related components?
DRex Electronics has them in stock:
- ✅ULN2003AN chipset andmodules.
- 28BYJ-48 stepper motor and motor controller kit
- Relay cards, connectors, resistors and prototyping tools.
- Other Darlington matrices and power drivers
We offer reliable components for embedded engineers, hobbyists, OEMs and educators with worldwide delivery and from trusted sources.
See DRex Electronics full product range.
Conclusions
TheULN2003AN is an excellent IC for easy control of high amp devices. Its integrated Darlington pairs, built-in protection diodes and TTL-compatible inputs make it an ideal bridge between microcontrollers and real power devices.
Are you ready to harness the power of the ULN2003AN?
🛠️ Visit DRex Electronics today to shop for real controller ICs and everything you need to build your next automation, robotics or control project.
