说明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.
- 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")
|Part Number||Reset Thresh.|
|Reset Out||tRESET||Watchdog Feature||Supervisor Features||Reset Thresh. Accur.|
|(min)||(@ +25°C)||(max)||(See Notes)|
|DS1231||3.3 to 5.5|
|85ms to 300ms||No Watchdog||Power Fail Comparator/Low Battery Detect||2.5||2000|