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 TimerâPreset 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
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