Microprocessor Supervisory Reset Circuits - Maxim
Description
19-2523; Rev 0; 7/02
Microprocessor Supervisory Reset Circuits with Edge-Triggered, One-Shot Manual Reset
General Description
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 MR asserts 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.
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.
Features
o Precision Factory-Set Reset Threshold Voltages for +5.
0V, +3.
3V, +3.
0V, +2.
5V, and +1.
8V Supplies o Edge-Triggered Manual Reset Input with OneShot Pulsed Reset Output o Two Reset Timeout Period Options (150ms or 1200ms min) o Immune to Short Voltage Transients o Low Supply Current (3µA at VCC = +1.
8V) o RESET Valid to VCC = +1V o Active-Low Ope...
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