# ATTINY25-20MUR

**Microchip Tech** · Microcontroller Units (MCUs/MPUs/SOCs) · QFN-20-EP(4x4)

ATTINY25-20MUR from Microchip Tech, in a QFN-20-EP(4x4). 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 | PB5 | bidirectional | Port B bit 5 with alternate functions PCINT5/RESET/ADC0/dW; a low level longer than the minimum pulse length on RESET generates a reset, and it can also be used as a (weak) I/O pin. |
| 2 | PB3 | bidirectional | Port B bit 3 with internal pull-up and alternate functions PCINT3/XTAL1/CLKI/OC1B/ADC3. |
| 3 | DNC | unconnected | Do Not Connect. |
| 4 | DNC | unconnected | Do Not Connect. |
| 5 | PB4 | bidirectional | Port B bit 4 with internal pull-up and alternate functions PCINT4/XTAL2/CLKO/OC1B/ADC2. |
| 6 | DNC | unconnected | Do Not Connect. |
| 7 | DNC | unconnected | Do Not Connect. |
| 8 | GND | power_in | Ground. |
| 9 | DNC | unconnected | Do Not Connect. |
| 10 | DNC | unconnected | Do Not Connect. |
| 11 | PB0 | bidirectional | Port B bit 0 with internal pull-up and alternate functions MOSI/DI/SDA/AIN0/OC0A/OC1A/AREF/PCINT0. |
| 12 | PB1 | bidirectional | Port B bit 1 with internal pull-up and alternate functions MISO/DO/AIN1/OC0B/OC1A/PCINT1. |
| 13 | DNC | unconnected | Do Not Connect. |
| 14 | PB2 | bidirectional | Port B bit 2 with internal pull-up and alternate functions SCK/USCK/SCL/ADC1/T0/INT0/PCINT2. |
| 15 | VCC | power_in | Supply voltage. |
| 16 | DNC | unconnected | Do Not Connect. |
| 17 | DNC | unconnected | Do Not Connect. |
| 18 | DNC | unconnected | Do Not Connect. |
| 19 | DNC | unconnected | Do Not Connect. |
| 20 | DNC | unconnected | Do Not Connect. |
| 21 | EP | passive | Exposed pad (from the footprint; not named in the datasheet pin table). |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Microchip Tech |
| Package | QFN-20-EP(4x4) |
| Category | Single Chip Microcomputer/Microcontroller |
| Pins | 21 |

## 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 supply voltage VCC (ATtiny25, non-V, 20 MHz grade) | VCC | 2.7 |  | 5.5 | V | ATtiny25 (not V) 2.7 - 5.5V; ordering table 20 MHz grade lists 2.7 - 5.5V | 1 |
| Speed grade, 20 MHz range | fCLK | 0 |  | 20 | MHz | @ 4.5 - 5.5V | 1 |
| Speed grade, 10 MHz range | fCLK | 0 |  | 10 | MHz | @ 2.7 - 5.5V | 1 |
| Industrial operating temperature range (MUR package, -20 grade) | TA | -40 |  | 85 | °C | Industrial (-40C to +85C) ordering row for ATtiny25-20MU / -20MUR (20M1 QFN) | 11 |

## Materials and finish

As the datasheet states them (page.json `metadata.appearance`; the 3D model's colours follow it).

| Part | Material | Colour / plating | Datasheet says | Page |
|---|---|---|---|---|
| contacts |  | tin | 3. Code indicators: H = NiPdAu lead finish, U/N = matte tin, R = tape & reel. 4. Can also be supplied in wafer form. Contact your local Atmel sales office for ordering information and minimum quantiti | 11 |

## CAD (KiCad official)

- Symbol: `ATTINY25-20MUR`
- Footprint: `Package_DFN_QFN:QFN-20-1EP_4x4mm_P0.5mm_EP2.5x2.5mm`
- 3D model: QFN-20-EP(4x4) (KiCad packages3D, STEP)
- 3D model files: `attiny25-20mur-etched.step` / `attiny25-20mur-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `attiny25-20mur.step` / `attiny25-20mur.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Microchip Tech datasheet](docs/attiny25-20mur-datasheet.pdf) (30 pp, sha256 `fcdc535a426347b5`, retrieved 2026-10-28, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-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/attiny25-20mur-datasheet.pdf)