Fixed 2.85 V rail, 800 mA — obsolete but still on the shelf
The STMicroelectronics LD1117S28TR is a fixed-output positive LDO regulator delivering 2.85 V at up to 800 mA. It is part of the LD1117 family, a workhorse low-dropout series used in post-regulation and local rail conditioning for mixed-signal boards, set-top boxes, and industrial control modules where a clean 2.85 V supply is needed.
A PSRR of 75 dB at 120 Hz attenuates full-wave-rectified ripple.
Protection built in — over-current and over-temperature
The LD1117S28TR integrates over-current and over-temperature protection, so a sustained output short or a high ambient temperature triggers thermal shutdown rather than letting the die exceed its safe operating area. This reduces the need for external supervisory circuitry in fault-prone environments like motor-adjacent boards or outdoor telecom modules.