The LM2931AZ50R is a fixed 5V output, 100 mA low-dropout linear regulator from STMicroelectronics. Maximum dropout is 0.6 V at 100 mA output, so the input rail needs at least 5.6 V to hold regulation at full load. Below that headroom the output starts to drop out — budget the margin in the front-end supply design.
Dropout and quiescent current at the load corner
The 1 mA Iq is modest for a 100 mA LDO; it does not dominate the efficiency budget in always-on loads, but it is not a micropower part either. Protection features include current limit and thermal shutdown — no reverse-current or reverse-voltage protection is listed, so the output should not be forced above the input in a dual-supply scenario.
Active production, through-hole package
Lifecycle status is Active. ROHS3 compliant. Packaged in TO-92-3 with formed leads (TO-226AA) — a through-hole footprint that mates with 0.100-inch pitch breadboard or PCB holes.