ULN2803A Darlington Array

@@ -0,0 +1,59 @@+# ULN2803A++**Texas Instruments** · Transistor Array / Driver · SOIC-18++The ULN2803A is an array of eight NPN Darlington pairs with high-voltage, high-current outputs and common-cathode flyback clamp diodes. Each channel sinks up to 500 mA at 50 V from a logic-level input, making it a standard way to drive relays, solenoids, unipolar stepper motors, and LED banks.++## Pinout++| Pin | Name | Type | Function |+|---|---|---|---|+| 1 | 1B | input | Channel 1 Darlington base input. Drives channel 1 output through 2.7kΩ series base resistor; compatible with TTL/CMOS logic up to VI(max)=30V. |+| 2 | 2B | input | Channel 2 Darlington base input. Drives channel 2 output through 2.7kΩ series base resistor. |+| 3 | 3B | input | Channel 3 Darlington base input. Drives channel 3 output through 2.7kΩ series base resistor. |+| 4 | 4B | input | Channel 4 Darlington base input. Drives channel 4 output through 2.7kΩ series base resistor. |+| 5 | 5B | input | Channel 5 Darlington base input. Drives channel 5 output through 2.7kΩ series base resistor. |+| 6 | 6B | input | Channel 6 Darlington base input. Drives channel 6 output through 2.7kΩ series base resistor. |+| 7 | 7B | input | Channel 7 Darlington base input. Drives channel 7 output through 2.7kΩ series base resistor. |+| 8 | 8B | input | Channel 8 Darlington base input. Drives channel 8 output through 2.7kΩ series base resistor. |+| 9 | GND | power_in | Common emitter of all eight Darlington pairs. Typically tied to system ground; also serves as the return for the input logic reference. |+| 10 | COM | power_in | Common cathode of the internal free-wheeling clamp diodes. Tie to the inductive-load supply (VSUP) so kickback energy is clamped when the Darlington turns off; may be left open when driving purely resistive loads. |+| 11 | 8C | output | Channel 8 Darlington open-collector output. Sinks up to 500mA per channel from loads returned to COM/VSUP (≤50V). |+| 12 | 7C | output | Channel 7 Darlington open-collector output. Sinks up to 500mA per channel. |+| 13 | 6C | output | Channel 6 Darlington open-collector output. Sinks up to 500mA per channel. |+| 14 | 5C | output | Channel 5 Darlington open-collector output. Sinks up to 500mA per channel. |+| 15 | 4C | output | Channel 4 Darlington open-collector output. Sinks up to 500mA per channel. |+| 16 | 3C | output | Channel 3 Darlington open-collector output. Sinks up to 500mA per channel. |+| 17 | 2C | output | Channel 2 Darlington open-collector output. Sinks up to 500mA per channel. |+| 18 | 1C | output | Channel 1 Darlington open-collector output. Sinks up to 500mA per channel. |++## Key specifications++| Parameter | Value |+|---|---|+| Type | 8-channel NPN Darlington array (sink) |+| Output voltage | 50 V max |+| Output current | 500 mA per channel (peak) |+| Input | Logic-level (2.7 V and 5 V compatible) |+| Clamp diodes | Integrated common-cathode (COM pin) |+| Operating temperature | -40 C to 85 C |++## Ordering variants++- `ULN2803ADW`++## CAD (KiCad official)++- Symbol: `uln2803a.kicad_sym`+- Footprint: `uln2803a.kicad_mod`+- 3D model: SOIC-18 wide body from KiCad `Package_SO/SOIC-18W_7.5x11.6mm_P1.27mm`.++## Provenance++Data extracted from the manufacturer datasheet, not a distributor listing:++- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/uln2803c.pdf) (21 pp, sha256 `12d7302794e2a590`, retrieved 2026-08-17, tier: manufacturer)+- **Extractor:** `ds2sf` (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.+- **CAD:** KiCad official libraries (CC-BY-SA 4.0).++[Datasheet PDF](docs/uln2803a-datasheet.pdf)

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