Capacitive Touch Sensor Controller - MPR121QR2

The MPR121QR2 is an I²C driven capacitive touch sensor controller, capable of managing up to twelve electrodes. The chip also has eight LED driving pins, which, when not configured to control electrodes, can be used to drive LEDs. The device also features a 13th simulated electrode that represents the simultaneous charging of all the electrodes connected together to allow for increased proximity detection in a touch panel or touch screen array.

The MPR121QR2 can operate at anywhere from 1.71 to 3.6VDC. It’s an Inter-Integrated Circuit (I²C) compliant device with an additional interrupt that is triggered any time a touch or release of a button is detected. The I²C address is also configurable via the ADDR pin.

It’s a tiny chip, with a 0.4mm pitch and a 3x3mm footprint. Look for a breakout board coming soon!

Features:

• 1.71 V to 3.6 V operation
• 29 μA supply current at 16 ms sample period
• 3 μA shutdown current
• 12 electrodes
• Continuous independent auto-calibration for each electrode input
• Separate touch and release trip thresholds for each electrode, providing hysteresis and electrode independence
• LED driver functionality with 8 shared LEDs
• I2C interface, with IRQ output to advise electrode status changes
• 3 mm x 3 mm x 0.65 mm 20 lead QFN package
• -40°C to +85°C operating temperature range

Documents:

• Datasheet
• Example Code (ATmega328)
• Freescale’s Product Page (for Application Notes, etc.)