What this part is and where it fits
The LM3S6100-IBZ25-A2T is a 32-bit ARM Cortex-M3 microcontroller from the Stellaris® 6000 series, built around a 25 MHz core with 64 KB of Flash and 16 KB of RAM. Its standout feature is an integrated Ethernet MAC, making it a natural fit for simple networked control — think Modbus TCP gateways, web-server endpoints, or data concentrators in industrial automation. The part also carries UART, SPI, SSI, and IrDA interfaces, plus a PWM unit and watchdog timer, so it can handle local sensor readout and actuation alongside the network stack. Rated for -40 to 85 °C and supplied at 2.25 V to 2.75 V, it suits factory-floor cabinets, outdoor telecom shelters, and other environments where extended temperature and a single low-voltage rail are the norm. The 108-ball BGA package (10x10 mm) means the board needs a reflow profile and via-in-pad capability — this is not a hand-solderable part.
Obsolete — what that means for your BOM
Texas Instruments has marked the LM3S6100-IBZ25-A2T as obsolete. There is no official successor order code. For an existing design that already qualifies this MCU, the only sourcing path is the independent surplus and broker channel. If you are qualifying a new build, the Stellaris family has been superseded by TI's Tiva C Series and later Cortex-M4F parts. Those are not pin-compatible, so a board respin is required. For a legacy BOM line that must stay on this exact footprint, the broker channel is the realistic option.
25 MHz core and 64 KB Flash — what they mean for the design
The 25 MHz Cortex-M3 runs a lightweight TCP/IP stack alongside a control loop polling sensors over SPI or UART. The 64 KB Flash and 16 KB RAM require careful memory partitioning for multiple socket connections.