NRND — plan the last buy or the migration
New designs should target the pin-compatible successors in the Stellaris family or migrate to a current TI Cortex-M4 portfolio part that matches the 50 MHz performance tier and 108-LFBGA footprint.
108-BGA 10x10 mm — layout constraints
The LM3S1165-IBZ50-A2T comes in a 108-LFBGA package with a 10x10 mm body (supplier device package 108-BGA). The 0.8 mm ball pitch is standard for BGA routing on a four-layer board, but the narrow 2.25 V–2.75 V supply rail needs a clean local LDO with low dropout and good transient response — the regulator output must stay inside that window under load steps.