LT SpiceIV: Imported LF353 Model Saturates In Every Simulation

Discussion in 'Electronics Resources' started by Twigg, Aug 9, 2015.

  1. Twigg

    Thread Starter New Member

    Jul 25, 2015
    Hi all,

    I've been trying to simulate a phase shifting circuit which uses a TI LF353P as a unity gain buffer and a non-inverting amplifier. But whenever I try to run a transient simulation of the circuit in LTSpice IV using a subcircuit model provided by TI (, the output saturates to a little under -8V. I unit tested the buffer in a separate schematic, with the same result. I've attached some screenshots of the results plus the schematic. When I built this circuit on a breadboard, I had no issues with the LF353 acting as either a buffer or as as inverting amp. I have also successfully simulated earlier versions of this circuit in TINA TI. I'm still learning how to use LTSpice IV, so I'd really appreciate it if someone could point out where I went wrong. Thanks!

    Here's how I imported the model: I downloaded the file found in the above link, and copy/pasted it to a folder I made for Third Party Models in the LTC folder. Then I opened the file in LTSpice IV. Then I right-clicked the .subckt line in the text and clicked 'Create Symbol' to auto-generate an LF353 symbol. I then went into the symbol file and gave the pins clearer labels:
    1 -> IN-
    2 -> IN+
    3 -> CC+
    4 -> CC-
    5 -> OUT
    When I added the component to the circuit, I clicked the 'Component' button in the toolbar and selected the symbol I had made from the 'Auto-Generated' folder.

    Thanks again!
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    Pin 1 of the .subckt is the non-inverting input + . I think you have it as the inverting input -
  3. Twigg

    Thread Starter New Member

    Jul 25, 2015
    D'oh! Thanks! Works just fine after I corrected the symbol. Dunno how I missed that.