32 MHz ARM Cortex-M3, 128 KB Flash — what it means for a low-power BOM
The STM32L151CBU6A is a 32-bit ARM Cortex-M3 MCU from STMicroelectronics, part of the STM32L1 ultra-low-power series. It runs at 32 MHz and carries 128 KB of Flash program memory, 32 KB of RAM, and 4 KB of embedded EEPROM — enough for a sensor-fusion algorithm or a communication protocol stack without external storage. The 1.8 V to 3.6 V supply range lets it run directly from a single Li-ion cell or two alkaline batteries, and the -40 °C to 85 °C temperature grade covers industrial and outdoor enclosures. On-chip peripherals include USB, I²C, SPI, UART, a 12-bit ADC with 16 channels, and a 12-bit DAC with two channels, so a typical application is a battery-powered data logger or a sensor node that talks to a host over USB without an external transceiver.
Supply range and USB — the fit for single-cell battery designs
The 1.8 V to 3.6 V supply (Vcc/Vdd) means this part runs on a single Li-ion cell or two alkaline cells without a regulator. USB connectivity is built in.
48-UFQFPN — board layout and thermal note
The 48-UFQFPN (7x7 mm) package requires a thermal pad on the PCB for both heat sinking and ground connection. The exposed pad is the main thermal path; a via array under the pad to a ground plane keeps junction temperature within spec even at the 85 °C end of the operating range.