General Description
The MAX792/MAX820 microprocessor (µP) supervisory circuits provide the most functions for power-supply and watchdog monitoring in systems without battery backup. Built-in features include the following:
• µP reset: Assertion of RESET and RESET outputs during
   power-up, power-down, and brownout conditions.
   RESET is guaranteed valid for VCC down to 1V.
• Manual-reset input.
• Two-stage power-fail warning: A separate low-line
   comparator compares VCC to a preset threshold
   120mV above the reset threshold; the low-line and
   reset thresholds can be programmed externally.
• Watchdog fault output: Assertion of WDO if the watchdog
   input is not toggled within a preset timeout
   period.
• Pulsed watchdog output: Advance warning of
   impending WDO assertion from watchdog timeout that
   causes hardware shutdown.
• Write protection of CMOS RAM, EEPROM, or other
   memory devices.
  
The MAX792 and MAX820 are identical, except the MAX820 guarantees higher low-line and reset threshold accuracy (±2%).

Features
♦ Manual-Reset Input
♦ 200ms Power-OK/Reset Time Delay
♦ Independent Watchdog Timer—Preset or Adjustable
♦ On-Board Gating of Chip-Enable Signals
♦ Memory Write-Cycle Completion
♦ 10ns (max) Chip-Enable Gate Propagation Delay
♦ Voltage Monitor for Overvoltage Warning
♦ ±2% Reset and Low-Line Threshold Accuracy
   (MAX820, external programming mode)

Applications
   Computers
   Controllers
   Intelligent Instruments
   Critical µP Power Monitoring