Dual-voltage supervisor in a 4-pin SC-70
The MAX6389XS29D3+T is a multi-voltage supervisor from Analog Devices that monitors two supply rails — one fixed at 2.93V and a second adjustable via external resistors — and asserts an active-low, open-drain reset output when either falls below its threshold.
Threshold selection and reset timing
The fixed threshold of 2.93V is intended for a 3.0V or 3.3V rail with typical tolerance — the supervisor trips before the rail drops below the processor's minimum operating voltage. The second channel's adjustable input lets the designer set a trip point for a lower-voltage core or I/O supply using a resistor divider. Both channels share a single open-drain output, so the reset signal is the wired-OR of the two undervoltage events. The 140ms minimum reset timeout is long enough to cover most power-supply ramp-up and hold-up capacitor discharge profiles, but short enough that the system does not linger in reset during a brief brownout.
Sourcing and compliance posture
It is available in tape-and-reel or cut-tape formats in the SC-82A/SOT-343 package that maps to a SC-70-4 footprint.