The STM32F303Zx from STMicroelectronics is a Space Qualified Microcontroller with Clock Rate 32 kHz to 32 MHz, Operating Frequency 72 MHz, Internal RAM Memory SRAM : 64 kB, Flash Memory 384 to 512 KB, Supply Voltage 2 to 3.6 V. Tags: Surface Mount. More details for STM32F303Zx can be seen below.