3 A adjustable LDO — what the ratings mean for the rail
The LT1764AEQ#PBF is a single-channel positive adjustable linear regulator rated for 3 A continuous output. Its maximum dropout voltage of 0.66 V at full load sets the minimum input-to-output headroom: feed it at least 1.21 V above the set output voltage to keep the pass element in regulation. The 63 dB PSRR at 120 Hz attenuates full-wave rectifier ripple, which matters when the LDO sits downstream of a bulk capacitor and the load is a sensitive analog rail or a noise-budgeted digital core. The 1.5 mA quiescent current is the current the regulator burns to run its internal bias — it flows to ground regardless of load. In a 3 A design that 1.5 mA is negligible, but if this rail is always-on in a battery-backed system, stack it against the load current to estimate standby draw. Protection features include over-current, over-temperature, and reverse polarity. The reverse-polarity clamp means the part survives a reversed input without blocking diode losses, but the tab is still the primary thermal path — the D2Pak (5-DDPAK) package relies on board copper for heat spreading. Junction temperature range of -40°C to 125°C covers industrial enclosures, outdoor telecom cabinets, and under-hood automotive auxiliary rails.
Active lifecycle — no LTB risk on this BOM line
The LT1764AEQ#PBF carries an active lifecycle status. No last-time-buy notice, no end-of-life window. For a production BOM this means the part can be qualified without obsolescence watch. The #PBF suffix confirms ROHS3 compliance — no exemption-based paperwork needed for EU or California markets.