3-Pin UC Supervisor Circuit

The FM1233A is a supervisor circuit that monitors a micropro- cessor power supply or other system voltage and issues a reset pulse when a fault condition exists. Several different threshold voltages are offered to accommodate 3.3V and 3.0V systems with different tolerances. FM1233A features a precision temperature-compensated volt- age reference and Comparator When VCC falls to the threshold voltage, a RESET pulse is issued, holding the output in the active state. When power rises above VTH, the reset remains asserted for a minimum period (tRST) to allow the system Clock and other circuits to stabilize. The reset output of FM1233A is of open-drain active low type. The FM1233A also CAN monitor a Switch closure on its output, enabling it to recognize an external reset from a pushbutton Switch or a P. In the case of a Switch the closure will be debounced by circuitry internal to the FM1233A. By Fairchild Semiconductor