STM8L101F3U6TR — 8-bit MCU for low-power control
The STMicroelectronics STM8L101F3U6TR is an 8-bit microcontroller from the STM8L EnergyLite series, built around the STM8 core and clocked at 16 MHz. On-chip peripherals include I²C, SPI, UART/USART, PWM, and an infrared encoder, all in a compact 20-UFQFPN (3x3 mm) package.
Memory budget — what fits in 8 KB Flash and 1.5 KB RAM
With 8 KB of Flash and 1.5 KB of RAM, this part is sized for a single-threaded control application — think a thermostat firmware, a pulse counter with Modbus framing, or a keypad scanner with LED PWM. The 2 KB EEPROM is a genuine advantage: it saves a separate serial EEPROM footprint and cost for calibration coefficients, serial numbers, or configuration tables. If your firmware image or runtime heap exceeds these numbers, you are looking at the STM8L101F2U6TR (4 KB Flash, 1 KB RAM) or stepping up to the STM8L151 series with larger memory options.
Supply and power — single-cell battery ready
For precision timing or USB applications, an external clock source can be fed in through the available oscillator pins.
Package and footprint — 20-UFQFPN 3x3 mm
The 20-UFQFPN (3x3 mm) package is a fine-pitch QFN with an exposed pad. The pad should be stitched to ground with several vias for thermal and electrical continuity. The 18 I/O lines give enough headroom for a small keypad, a character LCD, and one or two serial buses.
Temperature grade — industrial range
It does not carry an AEC-Q100 automotive grade — for under-hood or 125°C environments, look at the STM8A series. The -40°C low end is fine for cold storage or outdoor sensor nodes in temperate climates.
For dual-sourcing resilience, the STM8L101F3U6TR is pin-compatible with the STM8L101F2U6TR (4 KB Flash, 1 KB RAM) — the same package and pinout, just less memory. If your firmware fits in the smaller memory, the F2 variant is a valid second source for the same board.