ATMEGA328P-AU by Microchip: 8-bit RISC CPU, 20 MHz clock, 23 I/O lines. Ideal for industrial applications with SPI, TWI, USART connectivity and low power mode. Features include 2048 RAM bytes, 1024 EEPROM size, and 16384 ROM words.
BSS138LT3G by Onsemi is a N-CHANNEL FET with a min DS breakdown voltage of 50V. It is used for switching applications and has a max drain current of 0.2A and max drain-source on resistance of 3.5 ohm.
Vishay Sprague's ULN-2803A is an 8-bit peripheral driver with a max supply voltage of 3V. Featuring open-collector output characteristics, it offers built-in transient protections and operates b/w -20°C to 85°C. Ideal for applications requiring sink current flow direction, this rectangular-shaped driver has a terminal pitch of 2.54mm and turn-on/off time of 1us.
TEMPERATURE SENSOR,SWITCH/DIGITAL OUTPUT,SERIAL; Mounting Feature: SURFACE MOUNT; No. of Terminals: 8; Package Shape or Style: RECTANGULAR; Body Width: 3.9 inch; Maximum Supply Voltage: 5.5 V;