The LM2940CT-15: Maximum input voltage is 26V, so the part can regulate 15V from a 24V nominal supply with 2V of headroom above dropout. The 0.8V dropout at 1A means the input must stay above 15.8V to maintain regulation — a 12V input will not produce a regulated 15V output. For a 12V-to-15V boost, you need a switching converter, not this LDO. That Iq is high by modern LDO standards — expect ~150 mW of quiescent loss at 15V output, which the TO-220 tab can sink if the junction stays below 125°C. PSRR is 66 dB at 120 Hz, useful for filtering 100/120 Hz ripple from a rectified AC input. For higher-frequency switching noise, the PSRR rolls off — a post-filter LC stage may be needed if the supply comes from a switcher.
For volume or long-term contracts, evaluate a second-source or a newer LDO family before committing the BOM.
Protection features and thermal reality
Built-in protection covers overcurrent, overtemperature, reverse polarity, and short circuit. The TO-220-3 tab is the primary heat path — in a 1A, 15V output application with 5V input-output differential, expect 5W dissipation. That requires a heatsink; the tab is electrically common with ground, so no isolation pad is needed for a grounded heatsink.