Microchip Technology AT42QT2120-XUR

Overview

AT42QT2120-XUR from Microchip Technology is a 12-channel QTouchADC capacitive touch sensor IC supporting up to 12 keys, or 9 keys plus wheel/slider, with programmable I²C interface and standalone mode operation. It integrates spread-spectrum charge-transfer sensing, Adjacent Key Suppression (AKS®), self-calibration, and drift compensation. Designed for front-panel human-machine interfaces in industrial control panels, consumer appliances, and medical devices requiring robust touch detection through thick overlays.

For engineers reviewing the AT42QT2120-XUR datasheet, AT42QT2120-XUR pinout, AT42QT2120-XUR application, or AT42QT2120-XUR equivalent, key selection considerations include comms vs. standalone mode trade-offs, AKS group configuration, proximity/guard channel assignment, and I²C address (0x1C) compatibility with host controllers.

Technical Context

The AT42QT2120-XUR implements patented QTouchADC acquisition using spread-spectrum burst modulation to suppress RF emissions and external noise-eliminating need for external sampling capacitors. Its signal chain includes per-key detect threshold, 1–32-step detect integrator (DI), fixed 12.5% hysteresis, and dual-mode drift compensation (TTD/ATD).

Two operational modes define system integration: Comms Mode enables full I²C reconfiguration of thresholds, AKS groups, LP mode (1–255), TRD (160 ms–40.8 s), and guard assignment; Standalone Mode fixes parameters-including 10-count detect threshold, 30 s TRD, and hardwired guard on KEY1 and proximity on KEY0-with outputs driven directly on OUT2–OUT6.

Key Specifications

Pinout & Package

AT42QT2120-XUR is available in RoHS-compliant 20-pin SOIC/TSSOP (5.3 mm × 7.6 mm) and 20-pad VQFN (4 mm × 4 mm, 0.5 mm pitch) packages. Both variants support identical pin functions across Comms and Standalone modes, with pin numbering and layout optimized for PCB routing and ESD protection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar capacitive touch sensor applications.

Compared with AT42QT2120-XUR, AT42QT1012-MAHR offers reduced channel count and no wheel/slider capability-making it suitable only for compact key-only interfaces-while CY8CMBR2016-LQXI provides greater channel density and algorithmic flexibility at the cost of toolchain lock-in and absence of dedicated guard/proximity hardware channels.

Availability

AT42QT2120-XUR is available at Aetrix Electronics and suitable for industrial control panels, consumer appliance interfaces, medical device HMIs, and automotive trim applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for AT42QT2120-XUR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog components, and human-interface solutions with emphasis on reliability, longevity, and industrial-grade qualification.

The AT42QT2120-XUR belongs to Microchip's QTouch family of capacitive touch controllers, designed specifically for robust, low-cost, and easy-to-integrate touch sensing in harsh environments where mechanical switches fail.

FAQ

What is the I²C address of the AT42QT2120-XUR and can it be changed?

The AT42QT2120-XUR uses a fixed I²C slave address of 0x1C (28 decimal), which cannot be modified via hardware pins or software configuration. This simplifies bus arbitration in multi-device systems but requires careful address planning when other peripherals share the same bus. The AT42QT2120-XUR does not support address remapping, unlike some later-generation QTouch devices.

How does the AT42QT2120-XUR handle proximity detection in Standalone Mode?

In Standalone Mode, the AT42QT2120-XUR assigns KEY0 exclusively as a proximity channel with fixed 10-count detect threshold and automatic drift compensation. It operates independently of touch keys and asserts activity via the PXOUT pin (Pin 15 in SOIC/TSSOP, Pin 13 in VQFN). No host interaction is needed-the AT42QT2120-XUR drives PXOUT low on proximity event and holds until release.

Can the AT42QT2120-XUR drive LEDs directly without an external transistor?

Yes-in Standalone Mode, the AT42QT2120-XUR provides five push-pull output drivers (OUT2–OUT6) capable of sourcing up to 10 mA per pin at VDD = 3.3 V. These outputs go high during key press and can directly drive standard 2 mA LEDs with appropriate series resistors (e.g., 220 Ω @ 3.3 V). In Comms Mode, GPOs require explicit register writes and do not auto-assert on touch.

What is the maximum panel thickness supported by the AT42QT2120-XUR for wheel/slide functionality?

The AT42QT2120-XUR supports wheel and slider operation through up to 4 mm of glass or 3 mm of plastic overlay. This limitation arises from capacitive coupling attenuation-exceeding these thicknesses degrades spatial interpolation accuracy and increases false-negative rate. For optimal performance, wheel diameter should be 30–50 mm with 12 mm segment width, and slider length 50–100 mm.

Does the AT42QT2120-XUR require external capacitors for touch sensing?

No-the AT42QT2120-XUR uses QTouchADC charge-transfer technology that eliminates the need for external sampling capacitors (Cs). Only two external components are mandatory: a 0.1 µF ceramic bypass capacitor between VDD and VSS, and series Rs resistors (4.7 kΩ–20 kΩ) on each electrode line for ESD/RFI suppression. No timing or calibration capacitors are required.