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Problem with LM5111 Spice Model

Matthias Luh
Prodigy 100 points
Other Parts Discussed in Thread: LM5111

Hello,

I try to run a simulation in LTspice in order to test my design with the LM5111-1 Dual 5A Compound Gate Driver, driving a Infineon IPT004N03L.

However, I encounter a problem whenever the VEE port of the LM5111 is not directly connected to the ground node of LTspice. I created a simplified model that clearly shows the difference between a working and a non working circuit (see below/attached). I think some of the subcircuits within the LM5111-1 spice model are connected directly to node 0 (spice ground) instead of VEE, which is problematic if VEE is not connected to Ground/Node 0.
I tried to replace all " 0 " connections with " VEE " but spice threw an error: "Singular matrix: check node u2:_u11:vee Iteration No. 1"

The model I used in the example can be found here: www.ti.com/.../snvmad2

I also tried the other models of LM5111-1: www.ti.com/.../toolssoftware

Since the control voltage is not directly connected to ground but isolated in my design, the model doesn't work for me, I think? Is there a solution tto make it work or do you think I made a mistake in using or importing the model?

Thank you in advance,

Matthias

P.S.: Using LTspice 4.23h on a Windows 7 Enterprise 64bit

--------

Screenshot & zip file with LTspice circuit, Plot and LM5111-1 model

15-12-08_10-22_LM5111-1_bug.zip

  • 0
    TI__Mastermind 41310 points

    Matthias,

    We do not support LTSpice in general as we are not allowed to use it per LT's EULA. The model appears to be working correctly when the VEE pin is tied to ground, which is the only connection that it should be used for. Please refer to the datasheet concerning the VEE pin. It is specifically mentioned many times that it should be tied to ground only.

    You are probably correct in that many of our models have internal ground references built into the model. We do not recommend that customers modify the internals of any PSpice model that we provide.

     

  • 0 in reply to Britt Brooks - Online Design Tools
    Prodigy 100 points
    Hello,
    Thank you for your reply. When you say "It is specifically mentioned many times that it should be tied to ground only." - do you refer to the spice model or to the LM5111-1 itself? I do not intent to use it in a classical High-Side or Low-Side way (as used for H-Bridges or Inverters) but to enable a line that is not directly connected to Ground.
    Is that possible whenever the VCC to VEE and Input to VEE voltages are permanently driven within the specified ranges (5V for my application, no bootstrapping)? Or else, what could be a limiting factor?
    Thank you,
    Matthias
  • 0 in reply to Matthias Luh
    TI__Mastermind 41310 points

    Matthias,

    The datasheet refers to the actual device, not the spice model. I will see if I can find applications support for the device to see if it can be used with VEE tied to a non-zero voltage, however, I do not understand why VEE would not be tied to ground in your circuit.

    VEE on the IC should not impact the lower voltage across the FET you are driving. In your circuit that is not working, what is the ground reference for your supplies V_control1 and V_iso1? In the other circuit, V_supply2 is not referenced to ground.

    Let me see if I can get in touch with someone more familiar with the part and its capabilities.