Thermal and protection — 125 °C junction, built-in safeguards
The LP3964EMPX-2.5: The 9 mA quiescent current is typical for a 800 mA LDO of this generation — not a micropower part, but the trade-off is fast transient response on the 2.5 V rail. On-chip protection includes overcurrent limiting, overtemperature shutdown, and short-circuit current foldback. These prevent the regulator from damaging itself or the load when a downstream fault pulls the output low — the part recovers once the fault clears and the junction cools.
Package and enable — SOT-223-5 with logic-level shutdown
Housed in the SOT-223-5 (TO-261-5) surface-mount package, the LP3964EMPX-2.5 has an exposed thermal pad on the tab. The Enable pin (active high) lets a logic signal sequence the 2.5 V rail on after the input supply is stable. Pulled low, the regulator enters shutdown and drops the quiescent current to near zero — useful for power-gating blocks that only need the rail during active operation.
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