Full bridge inverter using UC22510 Not working LTspice

Hi everyone,

I am currently simulating a gate driver circuit using the UCC21520 in LTspice and running into some persistent stability issues. I’m hoping someone can spot if this is a model limitation, a simulator setting, or a circuit design error.

The Setup:

• Driver: UCC21520 (Isolated Dual-Channel Gate Driver).
• Simulator: LTspice.
• Application: Full bridge inverter for a charger.
• Key Components: I am using diodes D3 and D7 for .

The Problem:I am getting no output at the gate pins during standard simulation runs. However, I have observed the following anomalous behaviors:

1. D3 & D7 Removal: If I remove diodes D3 and D7 from the circuit, I start getting output, but only for the positive cycle (Low-side works, High-side fails/floats).
2. Random Success: On one specific occasion, the simulation ran perfectly without any circuit changes. I have not been able to reproduce this successful run since, which suggests a potential solver/convergence issue or an Initial Operating Point problem.

Troubleshooting Attempts:

• Verified pin connections and net names.
• Checked component values for the bootstrap network.
• Tested removing D3/D7 (results in partial output).

My Questions:

1. Has anyone experienced convergence issues with the unencrypted UCC21520 model in LTspice?

I have my schematic and the below.

Thanks in advance for your help.