LTC6993

I am using an LTC6993-3 timer chip and I am using it to generate a positive output pulse of approximately 27 seconds.  It is triggered from a high to low transition on the trigger pin and this transition is produced by a comparator.  This device is non-retriggerable.  My set resistor is 649 KΩ and my top DIV resistor is 1 MΩ and the bottom DIV resistor is 887 KΩ.  Most of the time i get the 27 second pulse out but sometimes the positive out is so short in time that it is hard to find.  Is there a time between the trigger signal being received and the output changing states during which the LTC6993-3 trigger signal can be overridden?  Does anyone have a suggestion for what could be causing this?  The environment is very noisy and I am having the board relayed out to try to address the noise issues.

Thank you for any help anyone can provide.

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  • Thanks for your question. 

    It sounds like your question is based around t-width or t-arm.    Can you draw a timing diagram of the input condition that causes this issue that you are describing?  

    Also, what supply voltage are you using.  This shouldn't matter, but if I try to reproduce what you are seeing, I'd like to have a setup as close as possible to yours. 

Reply
  • Thanks for your question. 

    It sounds like your question is based around t-width or t-arm.    Can you draw a timing diagram of the input condition that causes this issue that you are describing?  

    Also, what supply voltage are you using.  This shouldn't matter, but if I try to reproduce what you are seeing, I'd like to have a setup as close as possible to yours. 

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