What the 4.38V threshold and 140ms timeout mean for your board
The MAX823MEUK+T: That 140ms window gives the system oscillator, PLL, and memory controller time to settle before the processor starts executing code — without it, the CPU could boot into an undefined state on a marginal power-up. Active-low reset is the convention for most MCUs and SoCs — the supervisor pulls the RST pin low on fault and releases it after the timeout.
Temperature grade and package — fits industrial and automotive environments
A sensor node or ECU that sees 105°C on a summer-grade road still has 20°C of margin before the supervisor's own silicon hits its limit. The SOT-23-5 package (SC-74A, SOT-753 footprint) is a standard five-pin small-outline transistor package. It reflows with the same profile as the rest of the board — no special handling, no moisture-sensitive level above MSL 1 for most reel lots. The pinout is unambiguous: pin 1 is GND, pin 5 is VCC, and the reset output is on pin 4, which makes manual probing or a field swap straightforward if the board is laid out with a test point.
RoHS3 compliant — no exemption-based paperwork needed for EU or California market entry.