Power Monitor

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With precise, temperature-compensated comparators, the DS1231 Power Monitor Chip monitors input power and a 5V system power supply. If unsafe voltages are detected, a nonmaskable interrupt sends a warning signal to the processor in advance of power failure. Processing is unconditionally halted when power falls below a user-selectable 5% or 10% threshold level, with time to shutdown proportional to the available hold-up time of the power supply. Upon return of power, the DS1231 maintains reset until power conditions stabilize.

The DS1231 enhances system reliability by closely monitoring both processor and upstream power levels, warning of impending failure, and automatically suspending and restarting processor operation. An input sense also supports a connection to switched inputs such as an opto-isolator for LED function. All external reset components (i.e., pull-up resistor and delay timing capacitor) are contained in one package, saving space and cost.
DS1231: Block Diagram DS1231: Block Diagram Enlarge+

Key Features

  • Monitors input and power supply and warns of impending failure
  • Provides orderly shutdown
  • Initiates and holds processor reset until levels are unsafe
  • Tolerance threshold levels can be set for 5% or 10%
  • Automatically restarts processor on power-up
  • Pauses restart until system stabilizes
  • Operating range: 0°C to +70°C (DS1231 and DS1231S)
    -40°C to +85°C (DS1231-N and DS1231S-N)
  • Optional active-low NMI Hysteresis (200mV = "-20", 350mV = "-35", 500mV = "-50")

See parametric specs for Supervisors (1 Monitored Voltage) (250)

Part NumberReset Thresh.
Reset OuttRESETWatchdog FeatureSupervisor FeaturesReset Thresh. Accur.
min@ +25°CmaxSee Notes
DS1231 3.3 to 5.5
Active Low
Open Drain
85ms to 300msNo WatchdogPower Fail Comparator/Low Battery Detect2.52000
SOIC (W)/16
$3.83 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: DS1231.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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