The MAX6365-MAX6368 supervisory circuits simplify power-supply monitoring, battery-backup control functions, and memory write protection in microprocessor (µP) systems. The circuits significantly improve the size, accuracy, and reliability of modern systems with an ultra- small integrated solution. These devices perform four basic system functions: 1) Provide a µP reset output during VCC supply power- up, power-down, and brownout conditions. 2) Internally control VCC to backup-battery switching to maintain data or low-power operation for CMOS RAM, CMOS µPs, real-time clocks, and other digital logic when the main supply fails. 3) Provide memory write protection through internal chip-enable gating during supply or processor faults. 4) Include one of the following options: a manual reset input (MAX6365), a watchdog timer function (MAX6366), a battery-on output (MAX6367), or an auxiliary user-adjustable reset input (MAX6368). The MAX6365-MAX6368 operate from VCC supply volt- ages as low as 1.2V. The factory preset reset threshold voltages range from 2.32V to 4.63V (see Ordering Information). In addition, each part is offered in three reset output versions: push-pull active low, open-drain active low, or open-drain active high (see Selector Guide). The MAX6365-MAX6368 are available in minia- ture 8-pin SOT23 packages.