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TS3002 Simulation Model

Discussion in 'Electronic Design' started by rickman, Feb 18, 2013.

  1. rickman

    rickman Guest

    I'm looking at using this device as a low power VCO at 240 kHz. I would
    like to model it along with some of the associated circuitry, but the
    company doesn't provide a spice model. I was wondering if anyone knows
    how this thing works internally enough that a model could be created.

    http://touchstonesemi.com/products/ts3002

    It's an interesting little gadget.
     
  2. I recall Linear has something similar. But their models are custom
    behavioral thingies.

    Cheers
     
  3. rickman

    rickman Guest

    Don't know about LT. I think this part may be a second source for a
    part by Maxim or someone similar. I haven't found that part yet.

    I am working on my own model, but LTspice isn't always easy to use.
    Like many tools it is not easy to pick up again after you don't use it
    for a year or two. I can't seem to get a hierarchical model to work
    properly.

    I'm just constructing a functional model which will charge and discharge
    a cap from a pair of constant current sources as controlled by a FF
    triggered from the voltage trip points. That sounds like what they are
    doing based on the description in the data sheet. I'm not a proper
    analog designer so I don't know how their current source works. It
    seems to pass a current determined by the set resistor. I expect they
    are using current mirrors to scale a current in the resistor to the
    current to the cap. I don't think I need to simulate all the details.
    I just want to get a warm fuzzy that the control loop will work ok. The
    part I really have no idea about is how the resistors for the VCO input
    interact with the current source. This may be important. We'll see...

    I may have to "simulate" it on a PCB.
     
  4. rickman

    rickman Guest

    I was kinda hoping some of the chip gurus here would offer some opinions
    of how they thought this circuit might work. The company FAE has been
    very helpful in running some tests for me to make the chip run at my
    frequency and show that the VCO control will work. He hasn't been able
    to answer any of my detailed questions on how to get a fine control
    rather than a coarse adjustment. I also don't get any sense from him of
    how the chip works on the RSET pin. He just doesn't answer those
    questions and I don't want to bug him further. Its not like I'm going
    to be buying a million of these things.

    In reality I'd prefer to make my own VCXO, but I can't find a 240 kHz
    crystal. Whatever, I think I can get this to work even if I have to
    play with it on the workbench. I prefer to simulate and get it right
    the first time as my eyes make it hard to solder the small stuff these
    days.
     
  5. josephkk

    josephkk Guest

    OK i found them here:

    http://www.af4k.com/hc6ucrystals20000-21999khz.htm

    and here:

    http://www.golledge.com/pdf/products/xtl_sm/cc1v.pdf

    Without even trying hard

    ?-)
     
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