Microchip Technology AT42QT1481-AN

Overview

AT42QT1481-AN from Microchip Technology (formerly Atmel) is a 48-key QMatrix® capacitive touch sensor IC implementing patented transverse charge-transfer sensing with frequency hopping. It operates from 4.75–5.25 V, supports UART and SPI interfaces (up to 4 MHz), and delivers FMEA-compliant, IEC/EN/UL60730-certified touch detection for safety-critical human interface panels up to 50 mm thick glass.

For engineers reviewing the AT42QT1481-AN datasheet, AT42QT1481-AN pinout, AT42QT1481-AN application, or AT42QT1481-AN equivalent, this device is selected for robust multi-key touch control in Class B/C appliances, industrial HMIs, and medical devices requiring self-calibration, Adjacent Key Suppression®, and real-time signal strength reporting via simple byte-level commands.

Technical Context

The AT42QT1481-AN uses burst-mode transverse charge-transfer sensing across an 8×6 X-Y matrix (X0–X7, Y0A/Y0B–Y5A/Y5B), enabling up to 48 keys with individually configurable burst length (BL), dwell time, and detect integrator limits. Its dual-tier fast/normal detection integrators provide noise-immune touch confirmation without host intervention.

Hardware timing is anchored to a 16 MHz ±1% crystal/resonator (XT1/XT2), and all signal processing-including auto-drift compensation, saturation monitoring, and key failure reporting-is performed on-chip. The STATUS pin provides active-low event notification, while DRDY enables synchronous host polling with 100 µs grace period.

Key Specifications

Pinout & Package

AT42QT1481-AN is housed in a RoHS-compliant 44-pin 10 × 10 mm TQFP package with exposed thermal pad (not electrically connected). Pin functions are validated per Atmel datasheet 9621EX–AT42–07/2014.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT42QT1481-AN, the AT42QT2120-MAH reduces system footprint but sacrifices matrix scalability and thick-panel capability, while the CY8CMBR2044-LQXI offers I²C convenience yet shifts safety validation burden to the host MCU-making AT42QT1481-AN optimal for drop-in certified designs demanding 48-key density and 50 mm glass compatibility.

Availability

AT42QT1481-AN is available at Aetrix Electronics and suitable for home appliance control panels, industrial HMI front panels, and medical device user interfaces requiring stable component supply, long-term lifecycle assurance, and full safety documentation traceability.

Supply support for AT42QT1481-AN 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 acquired Atmel in 2016 and maintains full technical and manufacturing continuity for the AT42QT product family.

The AT42QT series was designed specifically for QMatrix®-based capacitive touch control in safety-critical applications-emphasizing FMEA compliance, self-calibration, and robustness against environmental stressors like humidity, temperature drift, and ESD.

FAQ

What is the maximum panel thickness supported by the AT42QT1481-AN?

The AT42QT1481-AN supports up to 50 mm of glass or 20 mm of plastic panel thickness, with key sensitivity individually adjustable per key via serial interface commands. Performance depends on electrode design and coupling; thicker panels require optimized burst length and sample resistor values to maintain ≥10-count signal swing for finger touch detection.

Does the AT42QT1481-AN require external microcontroller firmware for basic operation?

No-the AT42QT1481-AN performs all signal acquisition, filtering, calibration, and touch decision logic autonomously. A host microcontroller is only needed to issue configuration commands (e.g., set burst length or threshold) and read key status via UART or SPI. No firmware development is required for functional touch detection.

How does the AT42QT1481-AN achieve IEC/EN60730 compliance?

The AT42QT1481-AN integrates hardware-level FMEA-compliant self-tests covering oscillator stability, memory integrity, ADC functionality, and logic path verification. These tests execute at power-up and periodically during operation; their results must be read and validated by the host MCU to complete the safety chain per IEC/EN60730 Class B/C requirements.

Can the AT42QT1481-AN interface with both UART and SPI simultaneously?

No-the AT42QT1481-AN supports UART and SPI interfaces exclusively; they cannot operate concurrently. Interface selection is determined by hardware configuration (e.g., SS pin state at power-up) and fixed in firmware. Switching requires power cycle or hardware reset-designs must commit to one interface during layout.

What is the purpose of the DRDY pin on the AT42QT1481-AN?

The DRDY pin on the AT42QT1481-AN is an open-drain data-ready indicator that asserts low when UART or SPI data is valid for reading. Host systems must wait ≥100 µs after DRDY goes low before initiating a read transaction; this ensures internal processing completes and prevents data corruption or incomplete register reads in the AT42QT1481-AN.