100 mA ceiling — where this regulator fits
The LTC3631EDD#TRPBF is a 100 mA step-down buck regulator from Analog Devices, built for applications where the load current stays under that ceiling — think sensor nodes, isolated bias supplies, or always-on housekeeping rails in a 24 V industrial panel.
Positive or negative — the inverting trick
The output configuration is listed as positive or negative — that means the same IC can generate a negative rail from a positive input by wiring the load between the output and ground. An inverting topology without a separate inverter IC saves board space and BOM count. At 100 mA load the efficiency gain over a non-synchronous buck is a few percent — enough to matter in a battery-powered or thermally constrained design.
The 8-WFDFN exposed pad package (3x3 mm DFN) means the thermal path runs through the center pad to the PCB copper. The datasheet's thermal resistance figures assume a certain pad size and via pattern — a layout that skips the thermal vias under the pad will see higher junction temperature at the same load. Operating junction temperature range is -40°C to 125°C, which covers automotive under-hood and industrial enclosure ambient without derating the output current.
ROHS3 compliant per the manufacturer's declaration.