5V fixed rail with 1.5A headroom
The STMicroelectronics L7805C-D2TR is a fixed 5V positive linear regulator delivering up to 1.5A continuous output. It belongs to the L78xx family of three-terminal regulators that have been a staple for local on-card regulation in industrial and consumer designs for decades. The 35V maximum input voltage gives enough headroom for rectified and filtered DC rails from a 24VAC transformer or a 24V industrial supply. Built-in over-temperature and short-circuit protection means the regulator handles fault conditions without external crowbar or foldback circuitry.
62dB PSRR — why it matters for analog loads
The 62dB power-supply rejection ratio at 120Hz is the spec that separates this regulator from a generic 7805. At 120Hz — the full-wave rectifier ripple frequency for 60Hz mains — 62dB means the output ripple is attenuated by a factor of roughly 1250. For a 1Vpp input ripple, the output sees under 1mVpp. That matters when the 5V rail feeds an ADC reference, a precision op-amp, or a VCO where supply noise couples into the signal path. The 8mA quiescent current is typical for a bipolar 1.5A regulator; it adds about 0.4W dissipation at 5V output, which factors into the heatsink calculation.
D2PAK surface-mount — thermal reality
The D2PAK package has a large exposed copper tab for thermal management.
The L7805C-D2TR is listed as obsolete. STMicroelectronics has stopped production.