The LM3S1635-IQC50-A2: The 50 MHz clock rate is the ceiling for this Cortex-M3 core; at that speed the Flash requires one wait state for zero-wait access, so interrupt latency and tight loops benefit from placing time-critical code in SRAM. The 56 I/O in a 100-LQFP gives plenty of headroom for parallel sensor inputs or a parallel LCD bus, but the 4x10-bit ADC is limited — if you need more than four analog channels or 12-bit resolution, an external ADC or a different MCU tier is required.
Texas Instruments no longer manufactures this device, and no direct factory replacement has been assigned to this order code.