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detect pulse of 140ns and 50mv.

Discussion in 'General Electronics Discussion' started by [email protected], Sep 4, 2012.

  1. hiren.dave@bhuved.com

    [email protected]

    3
    0
    Sep 4, 2012
    Hi,

    i want to detect a pulse with 140ns and 50mV amplitude. i want to design such a circuit when pulse comes pic microcontroller should get an interrupt. how can i do that?

    thanks in advance...
     
  2. Laplace

    Laplace

    1,252
    184
    Apr 4, 2010
    One approach would be to use a high speed comparator such as the LMV7239. It has low input offset, low cost, and 5V single supply operation. For 50mV detection I would pre-bias the input with 15mV offset and use capacitive coupling for the pulse signal. Since the input signal is fast switching, there should not be a need to incorporate hysteresis but you will still need to follow high speed layout rules on the PCB to minimize feedback. The PIC has edge-triggered interrupt input but I'm not sure what the minimum hold time may be. The 140nS pulse may be sufficient for connecting directly to the interrupt input.
     
  3. hiren.dave@bhuved.com

    [email protected]

    3
    0
    Sep 4, 2012
    thanks for your reply. can you give me a circuit??
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,191
    2,693
    Jan 21, 2010
    Check the datasheet first.
     
  5. hiren.dave@bhuved.com

    [email protected]

    3
    0
    Sep 4, 2012
    hi friends,

    Finally i got the pulse using MC33274AP opamp and cd4098 pulse stretcher. thanks to all for being with me.
     
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