MAX820

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)

Input Voltage (with respect to GND)
VCC...........................................................................................-0.3V to +6V
All Other Inputs...........................................................-0.3V to (VCC + 0.3V)
Input Current
GND......................................................................................................25mA
All Other Outputs .................................................................................25mA
Continuous Power Dissipation (TA = +70°C)
Plastic DIP (derate 10.53mW/°C above +70°C) .............................842mW
Narrow SO (derate 9.52mW/°C above +70°C) ...............................762mW
CERDIP (derate 10.00mW/°C above +70°C)...................................800mW
Operating Temperature Ranges:
MAX792_C__/MAX820_C__....................................................0°C to +70°C
MAX792_E__/MAX820_E__ .................................................-40°C to +85°C
MAX792_MJE__/MAX820_MJE__.........................................-55°C to +125°C
Storage Temperature Range .............................................-65°C to +160°C
Lead Temperature (soldering, 10sec) ................................................+300°C

Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

The MAX792/MAX820 microprocessor (P) supervisory circuits provide the most functions for power-supply and watchdog monitoring in systems without battery backup. Built-in features include the following:

1) P reset: Assertion of RESET and RESET outputs during power-up, power-down, and brownout conditions. RESET is guaranteed valid for VCC down to 1V.

2) Manual-reset input.

3) 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.

4) Watchdog fault output: Assertion of WDO if the watchdog input is not toggled within a preset timeout period.

5) Pulsed watchdog output: Advance warning of impending WDO assertion from watchdog timeout that causes hardware shutdown.

6) 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%).