The LP38691DTX-3.3/NOPB is a single-output LDO that delivers a fixed 3.3 V at up to 500 mA.
Power-supply rejection ratio of 55 dB at 120 Hz means the regulator attenuates full-wave-rectified ripple by a factor of roughly 560×. For a 100 mVpp ripple on the input, the output sees under 180 µVpp at that frequency — relevant when the LDO follows a bulk capacitor without a downstream LC filter.
55 µA quiescent current, 100 µA max supply draw
For an always-on 3.3 V rail in a battery-powered device, the regulator's own draw sits well below 1 mW — negligible against the load current in most applications.
TO-252-3 package and thermal management
Over-temperature protection shuts the output down before the die exceeds its safe limit.