80 MHz Cortex-M4 with 256 KB Flash — the mid-range STM32L4 workhorse
The 52 GPIOs in a 64-LQFP package give you room for parallel LCD data buses or a bank of sensor interrupts without multiplexing. This is the part for designs that need more throughput and memory than the STM32L1 series (32 MHz, Cortex-M3) but don't require the 120 MHz / 1 MB tier of the STM32L4+.
On the connectivity side you get CANbus for industrial fieldbus, USB (device/host/OTG) for data logging or firmware updates over a thumb drive, QSPI for memory-mapped external Flash or PSRAM, and SAI for I²S audio codecs. The 16-channel 12-bit ADC and single 12-bit DAC cover analog sensing and setpoint outputs. Brown-out detect and DMA offload the core from housekeeping tasks.
STMicroelectronics lists the STM32L452RCT6 as Active. For dual-sourcing resilience, the STM32L151CBU6A (Cortex-M3, 32 MHz, 64-LQFP) is a functional cross-shop candidate if your firmware can tolerate the lower clock and memory — but it is not a pin-for-pin drop-in; review the peripheral set and supply voltage differences before committing the BOM.