I am unable to run ltspice simulation. I have tried changing the solver to alternate, adjusting Gmin and Trtol, Changing integration method. Always get the same error.

Error message: Analysis: time step too small; initial timepoint: trouble with schmitt-instance a:u1:4

ltspice circuit

  • \$\begingroup\$ Have you consulted the experts on the LTSpice Yahoo! group? \$\endgroup\$
    – Brian K1LI
    Commented May 15, 2019 at 17:41
  • \$\begingroup\$ It doesn't look like you defined any of the transient analysis parameters \$\endgroup\$
    – Charles H
    Commented May 15, 2019 at 17:47

1 Answer 1


The solver probably doesn't like the open ports SDCOM and SD on U1. If they really are supposed to be open, put a 1e6Ω or 1e9Ω to ground (or whatever value they should be set to). This helps the solver find the value on those ports.

They are probably high impedance to a gate of a mosfet or something like that, if so, its either a floating net or close to it, floating nets are hard to solve for, so you need a current and a voltage so the solver can solve the net.


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