A brownout reset is a circuit that causes a computer processor to reset (or reboot) in the event of a brownout, which is a significant drop in the power supply output voltage. Without a brownout reset circuit or an uninterruptible power supply (UPS) that maintains the full normal operating voltage for the processor when a brownout occurs, a processor can malfunction or lock up. In some cases, if a processor receives an abnormally low voltage and continues to operate anyway, it will produce nonsensical output. Brownouts can occur for brief intervals or over extended periods. They commonly occur on utility lines at times of exceptional power demand, such as during heat waves or after natural disasters. In a computer, a brownout can also occur as a result of a problem with the internal power supply that converts the AC utility power to the DC used by a computer's internal electronic components