Triple-rail monitoring in a six-pin SOT-23
The MAX6719UTSFD3+ is a triple power-supply monitor from Analog Devices that supervises three independent voltage rails: a fixed 1.05 V threshold, a fixed 2.925 V threshold, and one adjustable-threshold input that lets you set the trip point with an external resistor divider. When any monitored rail drops below its threshold, the part asserts a single active-low, open-drain reset output that stays low for a minimum of 140 ms after all rails return above threshold — long enough for the downstream processor or FPGA to complete its reset sequence.
Threshold selection and board-fit decisions
The 1.05 V threshold is a natural fit for monitoring a 1.2 V or 1.0 V core supply on a modern SoC or FPGA — the typical undervoltage trip sits about 12 % below the nominal rail. The 2.925 V threshold covers a 3.3 V I/O or auxiliary rail, tripping at roughly 11 % below nominal. The adjustable input uses an external resistor divider from the monitored rail to the reference pin. The internal reference is 0.6 V typical; the divider ratio sets the trip point anywhere above that. Because all three channels share a single reset output, the part is best suited for applications where any undervoltage on any rail should trigger a system reset — not for designs that need independent reset signals per rail.