15 V fixed rail for industrial and automotive auxiliary supplies
The LM2937ET-15-TI is a fixed 15 V output LDO regulator from Texas Instruments, delivering up to 500 mA continuous current. The 15 V rail is useful for powering op-amp front-ends, relay coils, or gate-drive bias circuits that need a clean, regulated supply above the 12 V bus. Output configuration is positive fixed — no external resistor divider needed for voltage setting. The single regulator channel keeps the BOM count low for a dedicated rail.
Sizing the input-output differential for dropout
Maximum dropout is 1 V at 50 mA load. At the full 500 mA rating, expect dropout to rise well above 1 V — the datasheet curve (not reproduced here) shows the trade-off. For a 15 V output, the input must stay above roughly 16 V at light load and higher at full load to maintain regulation. Maximum input voltage is 26 V, giving a 10 V headroom at 16 V input. Dropout is not the limiting factor here; thermal dissipation in the TO-220-3 package will be. At 500 mA and 26 V in, the LDO dissipates over 5 W — a heatsink is mandatory.
Protection features and temperature grade for harsh environments
On-chip protection includes over-temperature shutdown, reverse polarity protection, and short-circuit current limiting. These features let the regulator survive a miswired input or a sustained output short without external clamp diodes or crowbar circuits. The TO-220-3 package with a heatsink can handle the junction temperature at high load.