5V fixed LDO in DPAK — 1.5A rail with 64dB PSRR
The STMicroelectronics LD29150DT50R is a fixed 5V positive-output LDO regulator in the DPAK (TO-252-3) surface-mount package, delivering 1.5A continuous current. It is a single-regulator device with overcurrent and overtemperature protection built in. The 0.7V maximum dropout at the full 1.5A load means the input rail must stay above 5.7V to maintain regulation — a 5V rail from a 6V or 7.5V bus has comfortable headroom, but a 5.2V supply would drop out under load.
PSRR and noise rejection — 64dB at 120Hz
The LD29150DT50R provides 64dB of power-supply rejection at 120Hz. This is the ripple-rejection figure that matters when the input comes from a full-wave rectified or switching supply — 64dB attenuation at the fundamental ripple frequency means the output sees roughly 0.06% of the input ripple amplitude at that frequency. For a 100mVpp ripple on the input at 120Hz, the output ripple would be suppressed to about 63µVpp — clean enough for most analog front-end rails, though the PSRR rolls off at higher frequencies, so post-regulation filtering may be needed for noise above a few kilohertz.
Industrial temperature range and quiescent draw
The 180µA typical quiescent current keeps the self-heating low at light loads — the regulator's own dissipation at no load is under 1mW. Maximum supply current is 80mA, which includes the pass-element drive; at full 1.5A output the efficiency is dominated by the dropout voltage, not the bias current.
DPAK package — thermal and layout notes
The tab is the output (Vout) potential, so the thermal pad must be electrically isolated or connected to the output rail. The two signal pins are gate and sense; the tab carries the output current.