General Description
The FM1233A is a supervisor circuit that monitors a microprocessor 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 voltage 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 µP. In the case of a switch, the closure will be debounced by circuitry internal to the FM1233A.

FEATUREs
■ Precision monitoring of 3.3V and lower voltage
   microprocessor systems
■ VTH values of 3.08V, 2.88V and 2.72V
■ Automatic restart of microprocessor after power failure
■ Reset Timeout Period Choice:
   – Options AC and AD: 140ms (min)/256ms (typ)
   – Option ABA: 17ms (min)/32ms (typ)
   – Available on request: 64ms (typ) and 128ms (typ)
■ Internal 5kΩ pull-up resistor
■ Operating Temperature -40°C to +105°C
■ Monitors external pushbutton override
■ Internal switch debounce circuitry
■ SOT23-3 package