MAX821

The MAX821/MAX822 microprocessor (P) supervisory circuits monitor power supplies in P and digital systems. They provide excellent circuit reliability and low cost by eliminating external components and adjustments when used with 5V-powered or 3V-powered circuits. The MAX821/MAX822 also provide a power-on reset timeout delay that is pin selectable to 1ms (max), 20ms (min), or 100ms (min).

These devices perform a single function: they assert a reset signal whenever the Vcc supply voltage falls below a preset threshold, and they keep reset asserted for the pin-selected reset timeout delay after Vcc has risen above the reset threshold. The only difference between the two devices is that the MAX821 has an active-low RESET output (which is guaranteed to be in the correct state for Vcc down to 1V), while the MAX822 has an active-high RESET output. The reset comparator is designed to ignore fast transients on Vcc. Reset thresholds suitable for operation with a variety of supply voltages are available.

Low supply current makes the MAX821/MAX822 ideal for use in portable equipment. These devices come in a 4-pin SOT143 package.