# MCP23S09-E

**Microchip Tech** · I/O Expanders · QFN-16-EP(3x3)

MCP23S09-E from Microchip Tech, in a QFN-16-EP(3x3). Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VSS | power_in | Ground (high-current capable). |
| 2 | SCK | input | Serial clock input for the SPI interface. |
| 3 | VDD | power_in | Power supply pin (high-current capable), operating range 1.8V to 5.5V. |
| 4 | CS | input | Chip select input for the SPI interface. |
| 5 | SI | input | Serial data input for the SPI interface. |
| 6 | SO | output | Serial data output for the SPI interface. |
| 7 | RESET | input | Hardware reset input, must be externally biased. |
| 8 | INT | output | Interrupt output for the port, configurable as active-high, active-low or open-drain. |
| 9 | GP0 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 10 | GP1 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 11 | GP2 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 12 | GP3 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 13 | GP4 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 14 | GP5 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 15 | GP6 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 16 | GP7 | bidirectional | Bidirectional I/O pin with 5.5V tolerant input and open-drain output, can be enabled for interrupt-on-change and/or internal pull-up resistor. |
| 17 | EP | passive | Exposed thermal pad, can be left floating or connected to VSS. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Microchip Tech |
| Package | QFN-16-EP(3x3) |
| Category | Interface ICs |
| Pins | 17 |

## CAD (KiCad official)

- Symbol: `MCP23S09-E`
- Footprint: `Package_DFN_QFN:QFN-16-1EP_3x3mm_P0.5mm_EP1.7x1.7mm`
- 3D model: QFN-16-EP(3x3) (KiCad packages3D, STEP)
- 3D model files: `mcp23s09-e-etched.step` / `mcp23s09-e-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `mcp23s09-e.step` / `mcp23s09-e.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Microchip Tech datasheet](docs/mcp23s09-e-datasheet.pdf) (52 pp, sha256 `70744ea2313e65a6`, retrieved 2026-10-26, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text), consensus `claude-sonnet-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/mcp23s09-e-datasheet.pdf)