Viewing gate drive waveform on "disconnected" LLC converter?

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cupoftea

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Hi,
We are using ICE2HS01G LLC controller for 2kW offline LLC (390Vin) at 70kHz.

We have a zero ohm link to each LLC FET gate, and will at first disconnect this so that we can view the gate drive signals without powering into a load. We will then be able to see the gate rise times etc etc….then we can reconnect the gate drive to the FETs and let it loose with a real load.

…So, do you agree, that to avoid the ICE2HS01G from powering down due to detecting no feedback in this time, we will have to …

1….Adjust the LOAD pin divider so that LOAD pin gets ~1V (0.15V < LOAD pin < 1.8V)?
2….See that VMC pin has just a 10k resistor to ground (to disable burst mode)?
3…Anything else?

We wish to see the gate drive, as all the complimentary drive gate drive IC’s on the market (TC4428, MIC4128,TC1428, etc etc) are very weak and have a maximum of 1.5A of gate drive (Luckily being LLC, the turn ON does not have to be super-fast.

LTspice and jpeg scm attached
 

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  • LLC with chosen gate drive transformer.zip
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