50 MHz Cortex-M3 with 64 KB flash — memory and speed budget
The LM3S1138-IQC50-A2 runs a 32-bit ARM Cortex-M3 core at 50 MHz. On-chip memory is 64 KB of flash and 16 KB of SRAM. For a firmware engineer, that flash budget holds a moderate application stack plus a RTOS kernel; the SRAM leaves room for a few hundred bytes of heap and stack after the HAL footprint. Supply voltage is 2.25 V to 2.75 V — a narrow range that demands a regulated rail, not a direct battery.
NRND — last-time-buy window open
Texas Instruments lists the LM3S1138-IQC50-A2 as NRND (Not Recommended for New Designs). Existing production runs and BOM lines can still be filled through independent distribution; new designs should migrate to an active Stellaris or Tiva-C series part.
The MCU provides 46 general-purpose I/O lines and a peripheral set that includes I²C, SPI, SSI, UART/USART, and IrDA. An 8-channel 10-bit ADC handles slow analog inputs like temperature or potentiometer feedback. On-chip oscillators eliminate the external crystal for many applications. Built-in brown-out detect, POR, PWM, and watchdog timer cover supervisory and timing needs without external ICs. The 100-LQFP package (14x14 mm body) is a standard fine-pitch QFP — four-layer boards fan out the inner rows comfortably.