AT42QT2100-MU

Overview

The AT42QT2100-MU is a QTouch capacitive sensor IC supporting up to seven independent keys and one slider or wheel. It operates on a 2.0 V to 5.5 V supply within a -40°C to +85°C range. The device utilizes a full-duplex SPI interface with a maximum clock rate of 750 kHz, supplemented by DRDY and CHANGE status pins. Sensitivity is adjustable via external Cs capacitors ranging from 1 nF to 100 nF for keys and 4.7 nF to 220 nF for sliders. Key design parameters include a minimum electrode size of 5 mm x 5 mm and a center-to-center spacing of 6 mm.

Feature Summary

• Patented spread-spectrum charge-transfer technology provides superior noise rejection and EMI immunity.
• Integrated signal processing includes self-calibration, automatic drift compensation, and hardware-based moisture tolerance.
• Adjacent Key Suppression (AKS) prevents false triggers from adjacent electrodes during simultaneous contact.
• Flexible sensing configurations support linear sliders, rotary wheels, proximity detection, and discrete buttons.

Applications

• Portable consumer electronics requiring low-power touch interfaces
• Domestic appliances and audio/video equipment control panels
• PC peripherals and office equipment input devices

Procurement Notes

Verify the specific package variant against the datasheet; the MU suffix typically denotes the 32-pin MLF package. Confirm RoHS compliance and moisture sensitivity levels prior to PCB assembly. Ensure the host system supports the required SPI timing constraints and voltage levels for reliable communication.

Selection Notes

Select this component when a dedicated touch controller is needed to offload MCU resources. It is suitable for designs requiring high reliability in noisy environments due to its spread-spectrum operation. Consider the MLF package for compact layouts, ensuring adequate ground plane connectivity under the central pad.

Part Context

The AT42QT2100 belongs to Microchip's QTouch family, originally developed by Atmel. It serves as a specialized ASIC for capacitive sensing, distinct from general-purpose microcontrollers. The device integrates the analog front-end and digital signal processing required for robust touch detection without external sensors.

Replacement Considerations

Check the AT42QT2100-MUR for reel packaging options. Verify compatibility with newer revisions such as the AT42QT2100-EV or updated MLF/TQFP variants if pinout or package dimensions require adjustment.