A workhorse 5V rail in a D2PAK — what to expect
The STMicroelectronics L7805CD2T-TR is a fixed 5V positive-output linear voltage regulator delivering up to 1.5A in the surface-mount D2PAK (TO-263) package. It's the same 7805 topology that's been holding up 5V logic and analog rails for decades, now in a package that reflows onto a copper island without a through-hole tab. The 35V maximum input gives plenty of headroom for rectified DC from a 24V transformer or an unregulated bus, and the 62 dB PSRR at 120 Hz tells you it will knock down the 100/120 Hz ripple from a bulk capacitor before it reaches your load. Over-temperature and short-circuit protection are built in — the thermal shutdown saves the die when the heatsinking is marginal, and the current limit keeps a downstream fault from taking out the regulator itself.
Dropout voltage and the thermal reality of 1.5 A
Dropout is specified as 2V maximum at 1A output, typical lower. That means to hold a regulated 5V rail at a 1A load, the input needs to stay above 7V. At the full 1.5A rating, the dropout climbs, and the power dissipation (Vin – Vout) × Iout can exceed 10W in a worst-case 12V-in scenario. The D2PAK's exposed pad is the primary heat path; without a proper copper pour and thermal vias to a ground plane, the junction will hit the 125°C ceiling fast. The quiescent current runs 8 mA typical.
The D2PAK variant is a standard offering that ST continues to manufacture. ROHS3 compliant, no lead or halogen restrictions to trip up EU or California compliance.
The D2PAK package is common enough that multiple date codes and factory-origin lots are typically available. No special procurement gymnastics needed — just a clean RFQ with quantity and target delivery window.