ULN2803 Pinout
ULN2803A Darlington Array · 8-channel Darlington driver (8-channel version of the ULN2003) with freewheeling diodes.
| 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 | IN8 | Input | Input 8 |
| 9 | GND | GND | Ground |
| 10 | COM | Power | Freewheeling-diode common (connects to the load supply +) |
| 11 | OUT8 | Output | Output 8 (open-collector, current sink) |
| 12 | OUT7 | Output | Output 7 |
| 13 | OUT6 | Output | Output 6 |
| 14 | OUT5 | Output | Output 5 |
| 15 | OUT4 | Output | Output 4 |
| 16 | OUT3 | Output | Output 3 |
| 17 | OUT2 | Output | Output 2 |
| 18 | OUT1 | Output | Output 1 |
How to read the ULN2803 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
How do IN and OUT correspond?
IN1↔OUT18, IN2↔OUT17… i.e. INn maps to OUT(19−n); the outputs are in reverse order on the other side.
Where does COM (pin 10) connect?
Connect it to the positive supply of the load (relay/motor), as the common node of the internal freewheeling diodes, absorbing the reverse voltage at turn-off.
Difference from the ULN2003?
The ULN2803 is 8-channel (DIP-18); the ULN2003 is 7-channel (DIP-16). Per-channel characteristics are identical (open-collector, current sink, about 500mA/channel).
Pinout data comes from TI ULN2803A datasheet (standard DIP-18 numbering). Refer to the actual device datasheet as authoritative for the pinout.