64 KB Flash, 6 KB SRAM — what the memory split means for firmware fit
The 512 bytes of EEPROM are handy for calibration constants or fault logs that survive a power cycle, and the 20 MHz core speed keeps instruction cycles at 50 ns, fast enough for most sensor polling and UART handling at 115200 baud without bit-banging headaches.
That wide Vcc tolerance reduces BOM cost by eliminating a separate LDO in many battery-powered or industrial 5 V logic systems.
For a production BOM, this is a low-risk choice — no surprise obsolescence notice in the next year.
28-SSOP footprint and I/O count
The 28-pin SSOP body (0.209" wide, 5.30 mm) is a common footprint shared with many Microchip 8-bit MCUs, so a board layout for a previous Microchip 28-SSOP part often needs only a firmware recompile. You get 23 GPIOs, plus I²C, SMBus, SPI, and UART/USART peripherals, and a 20-channel 12-bit ADC plus one 10-bit DAC — enough for a sensor node or motor-control interface without external converters.