STM8S105K6U3ATR — 8-bit MCU in a 5x5 mm UFQFN for space-constrained industrial control
The STMicroelectronics STM8S105K6U3ATR is an 8-bit microcontroller from the STM8S series, built around the STM8 core running at 16 MHz. On-chip peripherals include a 7-channel 10-bit ADC, brown-out detect and reset, PWM, and a watchdog timer.
Memory and peripheral fit — what the 32 KB / 2 KB / 1 KB split means for your BOM
The 32 KB Flash (32K x 8) is the primary firmware store. For a typical motor-control or sensor-fusion application, that holds a modest RTOS kernel, communication stacks (LIN, Modbus over UART), and application code with room to spare. The 2 KB SRAM is the working memory — enough for a few 100-byte buffers and a small call stack. The 1 KB EEPROM is the key differentiator versus cheaper MCUs that require external EEPROM or emulate it in Flash: you can store calibration coefficients, fault logs, or configuration parameters directly, with no wear-leveling overhead at this density. The 7-channel 10-bit ADC covers analog inputs like potentiometers, current shunts, or NTC thermistors. If your design needs more than 7 analog inputs or 10-bit resolution, an external ADC or a larger MCU in the STM8S family would be the next step.
Package and thermal — UFQFN with exposed pad
The 32-UFQFN (5x5 mm) with exposed pad is a compact, low-profile package suited for dense PCBs. The mounting type is surface mount, so reflow profiling should follow ST's recommendations for the UFQFPN family.
Lifecycle — confirmed active production
STMicroelectronics lists the STM8S105K6U3ATR as Active.