3A adjustable LDO — headroom and ripple rejection
The Texas Instruments LMS1587IS-ADJ-TI is a positive adjustable LDO regulator delivering up to 3 A continuous output. Output voltage is set with an external resistor divider from 1.25 V minimum to 11.7 V maximum, given a 13 V max input rail. PSRR is 72 dB at 120 Hz, which attenuates rectified line ripple by a factor of ~4000, making this regulator suitable for powering sensitive analog front-ends or audio stages from a raw DC bus.
Thermal and protection envelope
The DDPAK/TO-263-3 package (3 leads plus exposed tab) is designed to sink heat through the PCB copper plane — the tab is the main thermal path, so the board layout must connect it to a sufficient copper area to keep junction rise within limits at 3 A. Built-in over-current and over-temperature protection latch the regulator off during fault conditions. Quiescent current is 13 mA typical, which is the regulator's own draw independent of load — budget this into the system's standby current calculation.
Lifecycle and compliance — active, but legacy solder
Product status is active per Texas Instruments — no last-time-buy window or end-of-life notice is in effect. The part is RoHS non-compliant, meaning it uses lead-based solder termination. This is acceptable in military, aerospace, or high-reliability applications that are exempt from RoHS, but it will not pass a standard RoHS assembly line without a waiver.