Dual-rail supervisor in a 5-pin SOT-23
The MAX6309UK29D3+T is a multi-voltage supervisor from Analog Devices that monitors two supply rails and asserts an active-low reset when either falls below its threshold — the primary channel is fixed at 2.93 V, the secondary is adjustable via external resistors. Reset remains asserted for a minimum of 140 ms after all monitored voltages return above threshold, giving the system power-on-reset hold time without external timing components.
Reset output and timing for the BOM
The push-pull, totem-pole output drives the reset line directly without a pull-up resistor — the output stays low during the fault and releases high when the supply is valid and the timeout expires.
Housed in a 5-pin SOT-23 (SC-74A), the part occupies minimal board area and shares the same footprint as many single-voltage supervisors — a layout that already routes two sense inputs can reuse the same land pattern.