Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset

The MAX6467/MAX6468 microprocessor (µP) supervisory circuits monitor single power-supply voltages from +1.8V to +5.0V and assert a reset if the supply voltage drops below its preset threshold. An edge-triggered, one-shot manual reset function ensures that the µP enters the reset mode for a fixed timeout period only, even in the event of a continuously asserted manual reset. The MAX6467/MAX6468 significantly improve system reliability compared to traditional manual reset supervisory circuits.

A variety of factory-trimmed threshold options accommodate different supply voltages and tolerances, eliminating external components. The factory-set thresholds range from +1.575V to +4.625V to monitor +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V supplies with various tolerances. Reset timeout periods of 150ms (min) and 1200ms (min) are available to accommodate different µP platforms.

A single, active-low RESET output asserts when VCC drops below its threshold or if the edge-triggered active-low MR asserts low. Active-low RESET remains low for the reset timeout period after VCC rises above its threshold and for a fixed, one-shot timeout period after a manual reset input falling edge. Active-low RESET remains valid as long as VCC remains above +1V. Open-drain (MAX6467) and push-pull (MAX6468) output options provide additional flexibility in the system design.

The MAX6467/MAX6468 are offered in the space-saving 4-pin SOT143 package and the ultra-small 4-pin SC70 package and are specified over the automotive (-40°C to +125°C) temperature range.

Applications

* Automotive Products * Cell Phones/PDAs * Digital Cameras * DSL Modems * Embedded Control Systems * Global Positioning Systems (GPS) * Industrial Equipment * Medical Devices * MP3 Players * Portable/Battery-Powered Equipment

* Precision Factory-Set Reset Threshold Voltages for +5.0V, +3.3V, +3.0V, +2.5V, and +1.8V Supplies

* Edge-Triggered Manual Reset Input with One-Shot Pulsed Reset Output

* Two Reset Timeout Period Options (150ms min or 1200ms min)

* Immune to Short Voltage Transients

* Low Supply Current (3µA at VCC = +1.8V)

* Active-Low RESET Valid to VCC = +1V

* Active-Low Open-Drain and Push-Pull Active-Low RESET Output Options

* -40°C to +125°C Operating Temperature Range

* Small 4-Pin SC70 and SOT143 Packages

* No External Components Required

* Pin Compatible with MAX811, MAX6315, MAX6384, and MAX6386

* AEC-Q100 Qualified, Refer to Ordering Information for Specific /V Parts