Three-rail sequencer with programmable thresholds
It monitors up to three supply rails and drives a push-pull, active-low reset output when any monitored voltage falls outside its programmed threshold. The part offers nine selectable threshold combinations, which lets you set undervoltage levels without external resistor dividers — a clean BOM play for multi-rail boards. The reset timeout is fixed at 140 ms by default but can be adjusted with an external capacitor, giving you control over power-up sequencing delays.
Three monitored voltages cover the typical core, I/O, and auxiliary rails on a mixed-signal board. The nine selectable threshold combinations map to common supply levels via a logic input, no resistor network. The push-pull output sinks and sources current, so it drives the reset line of an MCU or FPGA directly without a pull-up resistor. Active-low polarity matches the convention on most processors and CPLDs. The 140 ms timeout gives the bulk supply capacitors time to charge before the system starts; if your load needs a longer wait, the adjustable option buys that margin with one capacitor. Surface-mount 20-TQFN (4x4 mm) with an exposed pad pulls heat into the PCB ground plane. For a sequencer drawing microamps of quiescent current, thermal derating is not a concern, but the pad does improve solder-joint reliability under vibration.