Abstract: A delay line can be used to build a clock fail detector circuit that can determine if a system clock frequency falls below, or rises above, a predetermined value. This application note explains how to use the precise time delay generated by the delay line to build a "window" around the clock time period to determine if it rises above or drops below a specified time period range. An example is given using the DS1000 (now obsolete and replaced with the DS1100). The application note is relevant for all delay lines and can be used as an example to build programmable clock fail detectors using programmable delay lines. Such circuits could be used not only in built-in-test but also in production testing applications. The application note you have requested is available in Acrobat PDF format: APPLICATION NOTE 979: Tech Brief 36: Building a Pulse Width Discriminator Using a Delay Line (PDF, 448kB) A free Acrobat PDF reader is available from: http://www.adobe.com/products/acrobat/readstep.html We Want Your Feedback! Automatic Updates Would you like to be automatically notified when new application notes are published in your areas of interest? Sign up for EE-Mail™. More Information   APP 979: Feb 22, 2002 DS1004 5-Tap High-Speed Silicon Delay Line Full Data Sheet (PDF, 55kB) DS1005 5-Tap Silicon Delay Line Full Data Sheet (PDF, 63kB) DS1007 7-in-1 Silicon Delay Line Full Data Sheet (PDF, 57kB) DS1010 10-Tap Silicon Delay Line Full Data Sheet (PDF, 61kB) DS1013 3-in-1 Silicon Delay Line Full Data Sheet (PDF, 51kB) DS1020 Programmable 8 bit Silicon Delay Line Full Data Sheet (PDF, 200kB) DS1021 Programmable 8 bit Silicon Delay Line Full Data Sheet (PDF, 208kB) DS1023 8-Bit Programmable Timing Element Full Data Sheet (PDF, 256kB) Free Samples DS1033 3-in-1 Low Voltage Silicon Delay Line Full Data Sheet (PDF, 51kB) DS1035 3-in-1 High-Speed Silicon Delay Line Full Data Sheet (PDF, 51kB) DS1044 4-in-1 High-Speed Silicon Delay Line Full Data Sheet (PDF, 36kB) DS1045 4-Bit, Dual, Programmable Delay Line Full Data Sheet (PDF, 128kB) DS1100 5-Tap Economy Timing Element (Delay Line) Full Data Sheet (PDF, 168kB) Free Samples DS1100L 3-Volt 5-Tap Economy Timing Element (Delay Line) Full Data Sheet (PDF, 176kB) Free Samples DS1135 3-in-1 High-Speed Silicon Delay Line Full Data Sheet (PDF, 136kB) Free Samples DS1135L 3-Volt 3-in-1 High-Speed Silicon Delay Line Full Data Sheet (PDF, 144kB) Free Samples   Download, PDF Format (448kB)  AN979, AN 979, APP979, Appnote979, Appnote 979