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Commemorator IC for pressure sensor design

ZeroD
Expert 1470 points
Other Parts Discussed in Thread: NE555, TLV3701, LM555

Dear *,

i have a pressure sensor that has an output from 0-5V depending on the pressure.

I want to make a circuit when the pressure drops below a level that the circuit generates a square pulse with defined pulse duration.

I want to do it without a uC.

My idea is to use a compactor IC and a timer IC ( NE555) and a reference voltage IC.

Please can you suggest the Compactor, timer and reference IC for this application ( please note that i need all the ic to be in DIP package)

Best Regards,

D.

  • 0
    TI__Expert 4555 points

    D,

    You could use the TLV3701 as your comparator - I think it would be the best device in a DIP package for this usage case.

    I don't think it is necessary to have a reference voltage IC. You could power up the comparator using a 5V supply, and use a resistor divider to divide down the voltage down to 2.5V to feed into the non inverting pin of the comparator.

    For the timing aspect of this application, do you want to have a predefined pulse width as soon as the comparator output goes high and then have it go low regardless of whether the comparator is output HIGH or LOW, or would you like the timer to hold the output high for a delayed time until the threshold is no longer detected?

    The LM555 is a very popular and simple timer that is available in a DIP package. There are other spins of the 555 as well that prioritize precision or power consumption, I'd suggest you take a look at those as well.

    Regards,
    Jonny 

  • 0 in reply to Jonathan Nguyen
    Expert 1470 points
    Hi Jonathan,

    i like the idea of a resistor divider, this is simpler and i don't need high precision.

    The timer should react only on the transition from low to high, so when comparator goes from low to high the timer should generate a predefined *** width regardless of the compactor output at that time. This wold be the first option that you mentioned.

    is the LM555 god for this purpose? what is the mas pulse width with the LM555?

    Best Regards,
    D.
  • 0 in reply to ZeroD
    TI__Expert 4555 points
    D,

    The max pulse width for the LM555 depends on the time constant of the RC network assuming monostable operation. This link has several different application methods for 555 timers that you can consider for your application --> www.electronics-tutorials.ws/.../555_timer.html

    I focus mainly on comparators, if you have any questions regarding the LM555 or other timers, I would highly recommend opening a thread in the Clocks and Timing forums - there would be some much more experienced people to help you out on the timer side of things.

    Regards,
    Jonny