3A LDO with 1.2V dropout — the headroom math
The LP3873ESX-3.3 is a 3A fixed-output LDO from Texas Instruments. That margin shrinks if the input sees ripple or IR drop from the board trace.
PSRR profile — clean rail for sensitive analog
PSRR is specified at 73dB to 57dB at 120Hz. That 16dB spread across the band means the regulator attenuates 120Hz ripple from a rectified AC source by a factor of ~4500x at the low end, dropping to ~700x at the upper edge. For an ADC reference or an op-amp front-end, this keeps supply-induced spurs below the noise floor of a 16-bit converter on a 3.3V rail.
Industrial temp range and protection suite
Rated -40°C to 125°C operating junction temperature, the LP3873ESX-3.3 suits outdoor telecom, motor-drive control, or under-hood automotive modules where ambient heat exceeds 85°C. On-chip protection covers over-current, over-temperature, and short-circuit — the regulator folds back current during a fault and recovers when the junction cools, so a momentary load short does not latch the rail off.
DDPAK-5 package — thermal and layout notes
The DDPAK/TO-263-5 package (5 leads plus tab) has an exposed metal paddle on the bottom. The enable pin (Control Features: Enable) allows sequencing; pulling it low shuts the output off, reducing quiescent current to near zero.