LTspice for LTC3642

Discussion in 'General Electronics Chat' started by chenpenghao, Jan 4, 2012.

  1. chenpenghao

    Thread Starter New Member

    Jan 4, 2012
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    0
    i try to simulate LTC3642 on Ltspice.
    it should have the efficiency report for it,
    but the software told me he can not detect the steady state of circuit.
    can somebody help me?
    how can i get the efficiency report
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    In order to get an efficiency report, you must have exactly ONE voltage source, and exactly ONE current source in the simulation.

    You already have the one voltage source - you need a current source.

    Replace R3 with a current source. Rotate it so that the arrow is pointing down. Right-click on it ,click the advanced options button, and enter your desired load current and check the box next to "This is an active load".
     
    Last edited: Jan 4, 2012
  3. chenpenghao

    Thread Starter New Member

    Jan 4, 2012
    6
    0
    I have changed the resistor with a load current source, and check the box "this is an active load", but it seems still dosen't work.
    i am new with the LTspice, you help me a lot.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Here is the datasheet for the regulator:
    http://cds.linear.com/docs/Datasheet/3642fc.pdf
    The current sink should be no higher than 50mA.

    You might try running the test fixture for that iC. Right-click and select "Open test fixture..."
    Then try using your .tran statement after adding a 50mA current as a load.

    You should post an image of your updated schematic and simulation as it's running.

    I won't be available for several days starting Thursday morning. There are a few people on here who use LTSpice. If you don't get answers to this problem after posting your updated schematic and simulation results, then try the LTSpice group in Yahoo! Groups. You will need to sign up for a free Yahoo! account. You should be a member there anyway; it is a great resource. Lots of LTSpice models and good people.
     
  5. chenpenghao

    Thread Starter New Member

    Jan 4, 2012
    6
    0
    Thanks you very much
    you help me a lot
     
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