The LM809/810 microprocessor supervisory circuits can be used to monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down and brown-out conditions. The function of the LM809/810 is to monitor the VCC supply voltage, and assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The reset signal remains asserted for 240ms after VCC rises above the threshold. The LM809 has an active-low RESET output, while the LM810 has an active-high RESET output. Six standard reset voltage options are available, suitable for monitoring 5V, 3.3V, and 3V supply voltages. With a low supply current of only 15A, the LM809/810 are ideal for use in portable equipment. The LM809/LM810 are available in the 3-pin SOT23 package.