The MAX803/MAX809/MAX810 are microprocessor (μP) supervisory circuits used to monitor the power supplies in μP and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with +5V, +3.3V, +3.0V, or +2.5V powered circuits.

These circuits perform a single function: they assert a reset signal whenever the V_CC supply voltage declines below a preset threshold, keeping it asserted for at least 140ms after V_CC has risen above the reset threshold. Reset thresholds suitable for operation with a variety of supply voltages are available.

The MAX803 has an open-drain output stage, while the MAX809/MAX810 have push-pull outputs. The MAX803's open-drain active-low RESET output requires a pull-up resistor that can be connected to a voltage higher than V_CC. The MAX803/MAX809 have an active-low RESET output, while the MAX810 has an active-high RESET output. The reset comparator is designed to ignore fast transients on V_CC, and the outputs are guaranteed to be in the correct logic state for V_CC down to 1V.

Low supply current makes the MAX803/MAX809/MAX810 ideal for use in portable equipment. The MAX803 is available in a 3-pin SC70 package, and the MAX809/MAX810 are available in 3-pin SC70 or SOT23 packages.