What Is the ULN2003? 7-Channel Darlington Array: Pinout and Uses
The ULN2003 is a driver array with seven Darlington transistors in one package. It drives loads such as relays, solenoids and a stepper motor (28BYJ-48) from an MCU's weak output; each channel sinks ~500 mA (~50 V). It only sinks current (no H-bridge); it has a common (COM) flyback-diode pin for inductive loads.
The ULN2003 is a driver array with seven Darlington transistors in one package. It is used to drive loads such as relays, solenoids, a stepper motor (28BYJ-48) and high-current LEDs from a microcontroller's weak output. For the concept, see what is a transistor.
What is the ULN2003 used for?
Each of the 7 channels amplifies the logic signal at its input and sinks current from the load at its output. Its most common use is driving the 28BYJ-48 stepper motor (the ready ULN2003 board). It has a common (COM) flyback-diode pin for inductive loads such as relays and solenoids.
ULN2003 pinout (DIP-16)
| Pin | Function |
|---|---|
| 1–7 | Inputs (1B–7B) |
| 8 | GND |
| 9 | COM (common flyback-diode node — to load supply) |
| 10–16 | Outputs (7C–1C, open collector) |
The outputs are ordered reverse to the inputs (output 1 = pin 16, output 7 = pin 10).
Highlights
| Parameter | Value |
|---|---|
| Channels | 7 (Darlington, open collector) |
| Channel current | ~500 mA |
| Output voltage | up to ~50 V |
| Flyback | COM pin (inductive-load protection) |
Limitations
- It only sinks current; it is not bidirectional (no H-bridge) → for DC motor direction control use the L293D.
- Darlington drop ~1 V; it heats up at high current.
Equivalents and alternatives
- ULN2803: the 8-channel version.
- TIP120: a single high-current Darlington (our TIP120 article).
- MOSFET arrays: for more efficient switching.
Find it in our catalog
Use the ULN2003 search.