32 MHz Cortex-M0+ with 192 KB Flash — the ultra-low-power workhorse
It runs at 32 MHz and packs 192 KB of Flash program memory, 20 KB of SRAM, and 6 KB of true EEPROM — enough for moderate sensor fusion, data logging, or wireless protocol stacks without external storage. The 32-UFQFN package with exposed pad (5x5 mm footprint) keeps board area tight while the thermal pad helps pull heat from the core during sustained operation.
Temperature grade and supply — rated for harsh environments
The 1.65 V minimum supply is low enough to run on a near-depleted Li-SOCl₂ cell, while the 3.6 V ceiling covers standard 3.3 V and 3.0 V rails with margin. Brown-out detect and POR are integrated, so the reset circuit on the board can be minimal — just a decoupling cap and the external reset pin pulled high.
Memory configuration — Flash, SRAM, and EEPROM sizing
The 20 KB SRAM is adequate for moderate data buffers; if your application needs larger frame buffers or a heavy TCP/IP stack, you will want to check the RAM budget early. The 6 KB EEPROM is a standout: true byte-addressable, 100k-cycle endurance EEPROM on-chip, not emulated Flash. That means configuration parameters, calibration constants, and fault logs survive without wear-leveling code or external serial EEPROM. For designs that log data frequently, this saves both firmware complexity and a component slot.
For a production BOM, this means you can qualify the part now without planning a respin for an impending discontinuation. If you are dual-sourcing, the STM32L151CBU6A (Cortex-M3, 32 MHz, 37 I/O, -40°C to 85°C) is a functional alternative in a similar UFQFPN package, though the core architecture and I/O count differ — review the peripheral set and memory map before substituting.