ULN2003 Pinout
ULN2003A Darlington Array · 7-channel Darlington driver with freewheeling diodes; drives relays / stepper motors / lamps.
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | IN1 | Input | Input 1 (connects to MCU IO) |
| 2 | IN2 | Input | Input 2 |
| 3 | IN3 | Input | Input 3 |
| 4 | IN4 | Input | Input 4 |
| 5 | IN5 | Input | Input 5 |
| 6 | IN6 | Input | Input 6 |
| 7 | IN7 | Input | Input 7 |
| 8 | GND | GND | Ground |
| 9 | COM | Power | Freewheeling-diode common (connects to the load supply +) |
| 10 | OUT7 | Output | Output 7 (open-collector, current sink) |
| 11 | OUT6 | Output | Output 6 |
| 12 | OUT5 | Output | Output 5 |
| 13 | OUT4 | Output | Output 4 |
| 14 | OUT3 | Output | Output 3 |
| 15 | OUT2 | Output | Output 2 |
| 16 | OUT1 | Output | Output 1 |
How to read the ULN2003 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
Where does COM (pin 9) connect?
Connect it to the load's positive supply. It is the common node of the internal freewheeling diodes, absorbing the reverse voltage when a relay/motor is de-energized and protecting the driver transistors.
Can the output pull high?
No. The ULN2003 has open-collector (current-sink) outputs that only pull to ground; the other end of the load connects to the positive supply.
How do IN and OUT correspond?
IN1↔OUT16, IN2↔OUT15… i.e. INn maps to OUT(17−n); the OUT pins are arranged in reverse order on the other side.
Pinout data comes from TI ULN2003A datasheet (standard DIP-16 numbering). Refer to the actual device datasheet as authoritative for the pinout.