# ATTINY861A-SU

**Microchip Tech** · Microcontroller Units (MCUs/MPUs/SOCs) · SOIC-20-300mil

ATTINY861A-SU from Microchip Tech, in a SOIC-20-300mil. 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 | PB0 (MOSI/DI/SDA/OC1A/PCINT8) | bidirectional | Port B bit 0 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are MOSI/DI/SDA/OC1A/PCINT8. |
| 2 | PB1 (MISO/DO/OC1A/PCINT9) | bidirectional | Port B bit 1 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are MISO/DO/OC1A/PCINT9. |
| 3 | PB2 (SCK/USCK/SCL/OC1B/PCINT10) | bidirectional | Port B bit 2 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are SCK/USCK/SCL/OC1B/PCINT10. |
| 4 | PB3 | bidirectional | Port B bit 3 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are OC1B/PCINT11. |
| 5 | VCC | power_in | Supply voltage pin. |
| 6 | GND | power_in | Ground pin. |
| 7 | PB4 | bidirectional | Port B bit 4 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are ADC7/OC1D/CLKI/XTAL1/PCINT12. |
| 8 | PB5 | bidirectional | Port B bit 5 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are ADC8/OC1D/CLKO/XTAL2/PCINT13. |
| 9 | PB6 | bidirectional | Port B bit 6 is a bidirectional I/O pin with an individually selectable internal pull-up; its alternate functions are ADC9/INT0/T0/PCINT14. |
| 10 | PB7 (ADC10/RESET/PCINT15) | bidirectional | Port B bit 7 doubles as the RESET input: a low level longer than the minimum pulse length (Table 19-4) generates a reset, and when reset is disabled the pin can be used as a (weak) I/O pin. |
| 11 | PA7 (ADC6/AIN1/PCINT7) | bidirectional | Port A bit 7 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC6/AIN1/PCINT7. |
| 12 | PA6 (ADC5/AIN0/PCINT6) | bidirectional | Port A bit 6 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC5/AIN0/PCINT6. |
| 13 | PA5 (ADC4/AIN2/PCINT5) | bidirectional | Port A bit 5 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC4/AIN2/PCINT5. |
| 14 | PA4 (ADC3/ICP0/PCINT4) | bidirectional | Port A bit 4 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC3/ICP0/PCINT4. |
| 15 | AVCC | power_in | Analog supply for the ADC, analog comparator, BOD, internal voltage reference and Port A; it should be connected to VCC even if the ADC is unused, through a low-pass filter if the ADC is used. |
| 16 | AGND | power_in | Analog ground pin. |
| 17 | PA3 (AREF/PCINT3) | bidirectional | Port A bit 3 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are AREF/PCINT3. |
| 18 | PA2 (ADC2/INT1/USCK/SCL/PCINT2) | bidirectional | Port A bit 2 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC2/INT1/USCK/SCL/PCINT2. |
| 19 | PA1 (ADC1/DO/PCINT1) | bidirectional | Port A bit 1 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC1/DO/PCINT1. |
| 20 | PA0 (ADC0/DI/SDA/PCINT0) | bidirectional | Port A bit 0 is a bidirectional I/O pin with symmetrical drive and an individually selectable internal pull-up; its alternate functions are ADC0/DI/SDA/PCINT0. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Microchip Tech |
| Package | SOIC-20-300mil |
| Category | Single Chip Microcomputer/Microcontroller |
| Pins | 20 |

## Electrical characteristics

Limits as printed in the datasheet (page.json `metadata.characteristics` carries them as data).

| Parameter | Symbol | Min | Typ | Max | Unit | Conditions | Page |
|---|---|---|---|---|---|---|---|
| Operating voltage |  | 1.8 |  | 5.5 | V |  | 1 |
| Speed grade: 0-4 MHz |  | 0 |  | 4 | MHz | VCC = 1.8, 5.5V | 1 |
| Speed grade: 0-10 MHz |  | 0 |  | 10 | MHz | VCC = 2.7, 5.5V | 1 |
| Speed grade: 0-20 MHz |  | 0 |  | 20 | MHz | VCC = 4.5, 5.5V | 1 |
| Operating temperature (Industrial operational range) |  | -40 |  | 85 | °C | ATtiny861A-SU (20S2 SOIC), Industrial operational range | 13 |

## CAD (KiCad official)

- Symbol: `ATTINY861A-SU`
- Footprint: `Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm`
- 3D model: SOIC-20-300mil (KiCad packages3D, STEP)
- 3D model files: `attiny861a-su-etched.step` / `attiny861a-su-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `attiny861a-su.step` / `attiny861a-su.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Microchip Tech datasheet](docs/attiny861a-su-datasheet.pdf) (22 pp, sha256 `80d15581b2650413`, retrieved 2026-10-28, tier: lcsc)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-haiku-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/attiny861a-su-datasheet.pdf)