Processor Supervisor 4.37V 5V 16-Pin SOIC W

The DS1238A Micro Manager provides all the necessary functions for power supply monitoring, reset control, and memory backup in microprocessor-based systems. A precise internal voltage reference and comparator circuit monitor power supply status. When an out-of-tolerance condition occurs, the microprocessor reset and power-fail outputs are forced active, and static RAM control unconditionally write protects external memory. The DS1238A also provides early warning detection of a user-defined threshold by driving a non-maskable interrupt. External reset control is provided by a pushbutton reset debounce circuit connected to the RST/ pin. An internal watchdog timer can also force the reset outputs to the active state if the strobe input is not driven low prior to watchdog timeout. Oscillator control pins OSCSEL and OSCIN provide either external or internal clock timing for both the reset pulse width and the watchdog timeout period. The Watchdog Status and Reset Voltage Threshold are provided via WDS/ and RVT/ , respectively.

• Holds microprocessor in check during power transients
• Halts and restarts an out-of-control microprocessor
• Warns microprocessor of an impending power failure
• Converts CMOS SRAM into nonvolatile memory
• Unconditionally write protects memory when power supply is out of tolerance
• Delays write protection until completion of the current memory cycle
• Consumes less than 200 nA of battery current
• Controls external power switch for high current applications
• Debounces pushbutton reset
• Accurate 10% power supply monitoring
• Optional 5% power supply monitoring designated DS1238A-5
• Provides orderly shutdown in microprocessor applications
• Pin-for-pin compatible with MAX691
• Standard 16-pin DIP or space-saving 16-pin SOIC
• Optional industrial temperature range -40°C to +85°C