NCP1232

• Precision Voltage Monitor (Adjustable +4.5 V or +4.75 V)
• Reset Pulse Width (250 msec Min)
• No External Components
• Adjustable Watchdog Timer (150 msec, 600 msec or 1.2 sec)
• Debounced Manual Reset Input for External Override

*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 NCP1232 is a fullyintegrated processor supervisor. It provides three important functions to safeguard processor functionality: precision power on/off reset control, watchdog timer and external reset override. On powerup, the NCP1232 holds the processor in the reset state for a minimum of 250 msec after VCC is within tolerance to ensure a stable system startup. Microprocessor functionality is monitored by the onboard watchdog circuit.

The microprocessor must provide a periodic lowgoing signal on the ST input. Should the processor fail to supply this signal within the selected timeout period (150 msec, 600 msec or 1200 msec), an outofcontrol processor is indicated and the NCP1232 issues a processor reset as a result.The outputs of the NCP1232 are immediately driven active when the PB input is brought low by an external pushbutton switch or other electronic signal. When connected to a pushbutton switch, the NCP1232 provides contact debounce.

The NCP1232 is packaged in a spacesaving 8pin plastic SOIC package and requires no external components.