1.5A LDO for post-regulation and point-of-load rails
The LP3872ES-2.5/NOPB is a fixed 2.5V output LDO from Texas Instruments, delivering up to 1.5A from a TO-263-5 (DDPAK) surface-mount package. It is a single positive regulator with enable control and a maximum input voltage of 7V. With a maximum dropout voltage of 0.55V at the full 1.5A load, this part suits post-regulation from a 3.3V rail or a 5V bus where the headroom is tight — the 200 mV typical dropout at lower currents leaves margin for line transients.
PSRR and noise rejection in the audio band
Power supply rejection ratio is specified at 73 dB to 57 dB at 120 Hz — the higher figure at light loads drops as the output current increases. This means the regulator attenuates 120 Hz ripple from a rectified AC input by a factor of roughly 4500 at the low end, which is relevant for sensitive analog front-ends or audio circuits sharing the same supply. Quiescent current is 5 mA typical, rising to 15 mA maximum under all conditions. That Iq is higher than a micropower LDO but acceptable for a 1.5A-capable device where the load current dominates the efficiency calculation.
Thermal and protection envelope
The DDPAK package with its exposed tab requires a thermal pad on the PCB — the tab is the ground path and the primary heat sink, so the board copper area under the part sets the effective RθJA. The enable pin allows the regulator to be sequenced or gated by a system supervisor without an external MOSFET.