Loading ...
Sorry, an error occurred while loading the content.

AC dropout detector - LT1018

Expand Messages
  • Nicolae Sfetcu
    AC dropout detector - LT1018 This circuit uses an LT1018 dual comparator to form a AC dropout detector. Digital systems driven from the AC line often require
    Message 1 of 1 , Mar 8, 2001
    • 0 Attachment

      AC dropout detector - LT1018

      This circuit uses an LT1018 dual comparator to form a AC dropout detector. Digital systems driven from the AC line often require power dropout detection. Fast AC line dropout detection allows a memory store command to be issued before DC power falls. The AC input comes from the system power supply transformer secondary. Normally, the AC line turns on the LED every 8ms (1/2 cycle of the line), causing the output transistor to reset the 0.01uF capacitor. When the line drops out, the capacitor charges via the 33k resistor. The resultant ramp voltage is compared by the LT1018 to a +5v supply derived reference. In this case, the 2k-3k resistor resistors bias the LT1018 to go low within one cycle of AC line dropout. Typically, the DC regulator will supply 50ms-199ms of hold-up before it begins to sag.

    Your message has been successfully submitted and would be delivered to recipients shortly.