Supervisor for 5V rails — the 4.4V threshold catches brownout before the processor glitches
The MAX704CSA+ is a 1-channel battery-backup supervisor from Maxim Integrated, monitoring a single voltage rail with a 4.4V threshold. The 4.4V threshold is set for a nominal 5V supply — it triggers before the rail falls below the minimum operating voltage of most 5V logic and MCUs, giving the system a clean reset boundary rather than letting the processor run on a decaying rail.
The MAX704CSA+ drives an active-low reset output with a push-pull (totem-pole) stage. Unlike an open-drain output, this does not require an external pull-up resistor to VCC — the output swings rail-to-rail and drives the reset line directly into the processor's reset input. The 140ms minimum reset timeout gives the supply rail and oscillator time to stabilise before the processor is released from reset. This suits microcontrollers with slow-start PLLs or external crystal oscillators that need tens of milliseconds to reach steady-state frequency.
Active production, ROHS3 compliant — no last-time-buy pressure
The commercial temperature grade (0°C to 70°C) covers indoor equipment and most industrial enclosures without active cooling.