Microchip ATTINY2313A-SU, 8bit AVR Microcontroller, ATtiny2313, 20MHz, 2 kB Flash, 20-Pin SOIC

Atmel's tinyAVR® devices are optimized for applications that require performance, power efficiency, and ease-of-use in a small package. All picoPower devices are designed from the ground up for lowest possible power consumption.

Small, most compact package for applications where size is critical
Capacitive Touch
Fast and code efficient
High integration
1.8V to 5.5V operation (0.7V operation for ATtiny43U)