AT42QT1085-MU

Overview

The AT42QT1085-MU is an eight-channel QTouch capacitive touch sensor IC with an integrated haptic engine. It operates on a 2.0 V to 5.5 V supply and features a master/slave SPI interface supporting up to 750 kHz clock speeds. The device provides eight dedicated key channels, twelve dedicated bi-directional GPIO pins, and four additional configurable pins that can serve as either keys or GPIOs. It utilizes the QTouchADC measurement method with spread spectrum charge transfer for noise immunity. The package is a 32-pin MLF-32 (5 mm x 5 mm) RoHS compliant form factor.

Feature Summary

• Integrated haptic engine capable of triggering effects via touch detection or host microcontroller commands over SPI.
• Patented Adjacent Key Suppression technology ensures accurate key detection in close-proximity layouts.
• Advanced signal processing includes self-calibration, automatic drift compensation, and fast thermal tracking.
• Spread-spectrum operation suppresses external noise susceptibility and limits RF emissions.

Applications

• Consumer electronics requiring tactile feedback integration
• Industrial control panels with multiple input keys
• Appliances utilizing glass or plastic overlay interfaces

Procurement Notes

Verify the specific ordering suffix against official Microchip documentation to confirm package type and tape/reel specifications. Confirm current production status and lifecycle notifications prior to design-in, as component availability may vary by region and distributor.

Selection Notes

Select this component when an application requires both multi-key sensing and direct haptic feedback generation without external drivers. Ensure the host system supports SPI communication and has sufficient GPIO resources if utilizing the additional configurable pins alongside the primary touch keys.

Part Context

This part belongs to the AT42QT10xx series of QTouch sensor controllers from Microchip Technology. It is designed for applications needing robust touch sensing under various environmental conditions while providing immediate physical feedback through its built-in actuator drive capabilities.

Replacement Considerations

Consult Microchip's official product change notifications and discontinuance lists for valid substitute part numbers. Verify pin compatibility and software object protocol alignment before transitioning to alternative models within the same family.

FAQ

How does the device handle power supply fluctuations?

The AT42QT1085 automatically tracks and compensates for slow supply voltage changes due to temperature variations. However, rapid shifts may require a dedicated local voltage regulator to maintain sensitivity.

What is the function of the CHANGE pin?

The CHANGE pin is an open-drain output that asserts low to notify the host microcontroller that a message is waiting to be read via the SPI interface, eliminating the need for continuous polling.

Can unused GPIO pins be left floating?

Yes, according to the datasheet pinout descriptions, unused GPIO pins should be left open unless specific circuit requirements dictate otherwise.