Four-rail voltage watchdog in a SOT-23-6
It tracks three fixed thresholds at 2.19 V, 3.08 V, and 4.63 V, plus one adjustable input for a custom voltage, all in a six-pin SOT-23-6 package. The open-drain, active-low reset output asserts when any monitored voltage falls below its threshold and holds for a minimum of 140 ms after all rails recover — enough time for most power supplies and system clocks to stabilise before the processor starts. The SOT-23-6 footprint keeps the board area small, and the open-drain output lets multiple supervisors share a common pull-up resistor on a shared reset line.
Thresholds and the adjustable channel
Three of the four monitored thresholds are factory-set: 2.19 V, 3.08 V, and 4.63 V. The fourth channel is adjustable via an external resistor divider.
Reset timing and output drive
The 140 ms minimum reset timeout is long enough to ride through a brief brown-out without a false reset, but short enough that the system does not sit idle for a quarter-second after the rails come up. The open-drain output sinks current when the reset is asserted; you supply the pull-up resistor to the logic supply.
Lifecycle and compliance note
One catch: the part is RoHS non-compliant, so it is not suitable for new designs that must meet the EU RoHS directive. For legacy boards or military/aerospace projects where leaded solder is still specified, that is not a blocker — but a BOM reviewer should flag it if the assembly house requires RoHS.
Because it is an active part with no LTB risk, it can be specified into a production BOM with confidence that the supply chain will support it for the foreseeable future.