4.2V threshold — what it means for rail monitoring
The MAX6380UR42-T is a single-channel voltage detector from Analog Devices, monitoring one supply rail and asserting an active-low reset when the input drops below its 4.2V threshold. The open-drain output pulls low on a fault condition and releases when the rail recovers above the threshold plus hysteresis — the pull-up resistor connects to the monitored rail or a separate bias supply depending on the reset hold time needed. At 4.2V, this part is sized for 5V nominal rails where the undervoltage lockout or power-good window must trigger before the downstream logic loses state.
Package and board-fit — SOT-23-3 footprint
Housed in the three-lead SOT-23-3 package (also designated TO-236-3 and SC-59), the part occupies roughly 3×1.5 mm board area — suited for tight layouts where a supervisor must sit near the rail's own decoupling capacitor. The supplier device package is SOT-23-3; the land pattern matches the standard JEDEC MO-178 variant.
Active lifecycle — no obsolescence pressure
RoHS non-compliance is the main compliance flag: the part contains lead in the termination finish or die-attach material. For BOMs that require RoHS exemption (e.g. certain industrial and aerospace applications), this may be acceptable under the standard exemptions; for full RoHS-compliance requirements, the buyer should verify the acceptance criteria before committing the BOM line.