# AT42QT2120-SUR

**Microchip Tech** · Touch Sensors · SOIC-20-300mil

AT42QT2120-SUR 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 | KEY8/GPO6 | bidirectional | Comms mode: touch key 8 or general-purpose output GPO6; standalone mode: push-pull output for key 3; leave open if unused. |
| 2 | KEY7/GPO5 | bidirectional | Comms mode: touch key 7 or general-purpose output GPO5; standalone mode: push-pull output for key 2; leave open if unused. |
| 3 | KEY6/GPO4 | bidirectional | Comms mode: touch key 6 or general-purpose output GPO4; standalone mode: touch key 6; leave open if unused. |
| 4 | KEY5/GPO3 | bidirectional | Comms mode: touch key 5 or general-purpose output GPO3; standalone mode: touch key 5; leave open if unused. |
| 5 | KEY4/GPO2 | bidirectional | Comms mode: touch key 4 or general-purpose output GPO2; standalone mode: touch key 4; leave open if unused. |
| 6 | KEY3/GPO1 | bidirectional | Comms mode: touch key 3 or general-purpose output GPO1; standalone mode: touch key 3; leave open if unused. |
| 7 | KEY2/GPO0 | bidirectional | Comms mode: key/slider/wheel 2 or general-purpose output GPO0; standalone mode: touch key 2; leave open if unused. |
| 8 | KEY1 | bidirectional | Comms mode: key/slider/wheel 1; standalone mode: guard channel; leave open if unused. |
| 9 | KEY0 | bidirectional | Comms mode: key/slider/wheel 0; standalone mode: proximity channel; leave open if unused. |
| 10 | VSS | power_in | Ground reference for the device. |
| 11 | VDD | power_in | Supply pin; the device operates from 1.8 V to 5.5 V as stated in the features list. |
| 12 | MODE | input | Mode selection pin: connect to VSS for comms mode or to VDD for standalone mode. |
| 13 | SDA | bidirectional | Comms mode: I2C serial interface data as an open-drain line that must be pulled up to VDD; in standalone mode it is unused and should be pulled up to VDD. |
| 14 | RESET | input | Active-low reset with an internal 60 kΩ pull-up; tie to VDD if not used. |
| 15 | N/C | output | Comms mode: no connection; standalone mode: open-drain output for the proximity channel, leave open if unused. |
| 16 | SCL | bidirectional | Comms mode: I2C serial interface clock as an open-drain line that must be pulled up to VDD; in standalone mode it is unused and should be pulled up to VDD. |
| 17 | CHANGE | output | Comms mode: active-low state-change interrupt open-drain output requiring an external pull-up resistor; in standalone mode it is unused and should be pulled up to VDD. |
| 18 | KEY11/GPO9 | bidirectional | Comms mode: touch key 11 or general-purpose output GPO9; standalone mode: push-pull output for key 6; leave open if unused. |
| 19 | KEY10/GPO8 | bidirectional | Comms mode: touch key 10 or general-purpose output GPO8; standalone mode: push-pull output for key 5; leave open if unused. |
| 20 | KEY9/GPO7 | bidirectional | Comms mode: touch key 9 or general-purpose output GPO7; standalone mode: push-pull output for key 4; leave open if unused. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Microchip Tech |
| Package | SOIC-20-300mil |
| Category | Sensors |
| 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 |
|---|---|---|---|---|---|---|---|
| Supply voltage Vdd (absolute maximum) | Vdd | -0.5 |  | 6 | V |  | 30 |
| Max continuous pin current, any control or drive pin |  | -10 |  | 10 | mA | any control or drive pin | 30 |
| Storage temperature |  | -55 |  | 125 | °C |  | 30 |
| Operating temperature |  | -40 |  | 85 | °C |  | 30 |
| Supply voltage Vdd | Vdd | 1.8 |  | 5.5 | V |  | 30 |
| Supply ripple+noise |  | -25 |  | 25 | mV |  | 30 |
| Cx load capacitance per key | Cx | 1 |  | 30 | pF |  | 30 |
| Low output voltage | Vol |  |  | 0.6 | V | Vdd = 3.3 V, Cs = 10 nF, load = 5 pF, 32 ms default sleep, Ta = recommended range | 30 |
| Input leakage current | Iil | -1 |  | 1 | µA | Vdd = 3.3 V, Cs = 10 nF, load = 5 pF, 32 ms default sleep, Ta = recommended range | 30 |
| Sample frequency | FQT | 10.5 | 12.5 |  | kHz | Modulated spread-spectrum (chirp) | 31 |
| Burst modulation, percentage | Fm | 15 |  |  | % |  | 31 |
| I2C-compatible clock rate | FI2C |  |  | 400 | kHz |  | 31 |
| RESET pulse width |  | 2 |  |  | µs | 2 µs at 1.8 V | 31 |
| Power-up delay to operate/calibration time | TD |  | 230 |  | ms | Printed as <230 ms in the Typical column; can be longer if burst is very long | 31 |

## CAD (KiCad official)

- Symbol: `AT42QT2120-SUR`
- Footprint: `Package_SO:SOIC-20W_7.5x12.8mm_P1.27mm`
- 3D model: SOIC-20-300mil (KiCad packages3D, STEP)
- 3D model files: `at42qt2120-sur-etched.step` / `at42qt2120-sur-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `at42qt2120-sur.step` / `at42qt2120-sur.glb` are the bare package body.

## Provenance

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

- **Datasheet:** [Microchip Tech datasheet](https://jlcpcb.com/api/file/downloadByFileSystemAccessId/8588939666275897344) (46 pp, sha256 `1302c88dd32f1df3`, retrieved 2026-10-18, 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/at42qt2120-sur-datasheet.pdf)