Small-footprint 8-bit MCU for extended-temperature designs
The Microchip ATTINY424-XF is an 8-bit AVR microcontroller from the tinyAVR® 2 family, built around the AVR core running at 20 MHz.
Memory sizing — 4 KB Flash, 512 B RAM, 128 B EEPROM
The 4 KB Flash is enough for small control loops, bit-banged communication protocols, or a bootloader plus a modest application. The 512-byte RAM limits the stack and buffer sizes — any design with a large RTOS or multiple DMA buffers will outgrow this part quickly. The 128-byte EEPROM provides non-volatile storage for calibration constants, configuration parameters, or fault logs without needing external memory. The on-chip EEPROM endurance is typically 100,000 write cycles, adequate for most field-update scenarios.
At 20 MHz, the AVR core executes most instructions in a single clock cycle, giving a throughput of roughly 20 MIPS. This is enough for real-time tasks like PWM generation at tens of kHz, UART communication at 115200 baud, or reading the ADC at its maximum sampling rate. The accuracy is sufficient for UART and I²C timing, but for precision timing (e.g., CAN bus) an external clock source may be needed.
Package and PCB layout — 14-TSSOP
The 14-TSSOP package has a 0.173-inch body width and 0.65 mm lead pitch. A two-layer PCB can route all signals, but careful decoupling placement is needed — place a 100 nF ceramic capacitor within 2 mm of each VDD/VSS pair to keep the supply clean at 20 MHz. For high-volume reflow assembly, the Tape & Reel variant (ATTINY424-XU) is the usual choice.