LMG3522EVM-042: LMG342X-BB-EVM

Can you please provide more specific details on the assistance required here.

Thanks,

Subhransu

Thank you for your response!

Sure

We want to evaluate your LMG3522 device on our brake system for an elevator.

The brake is power from a 3 phase rectified High Voltage Source that comes after a main contactor.

The HV is rectified to 290VDC.

The Brake is engage by the HV_BRAKE1#  signal previously by a MOSFET.

So we replace this MOSFET with the lower LMG3522 on the LMG3522EVM-042 mounted on the

LMG342X-BB-EVM motherboard.  

Our PWM Signal from our control board is feed into the Motherboard's J8 connector.

We have a clean steady 12VDC signal wired to the motherboard to power the logic and 5V.

We have the AGND to our control Board GND witch is Isolated from the Main 290V rectified source.

But before we applied the rectified 3 phase source, we tested the wiring above with a single phase 120V

rectified source.  The units run just find.  After 30 minutes of running the Heat  Sink on the module only registered 35 C

even without the fan.  Nice!

Then the full 3 phase source was used to test the system but then we got the LS_FLT.

we can't seem to clear it and able to run it any more.  We removed the 3 Phase source 

and just power the motherboard with the 12VDC system and the LS_FLT appears.

We are wondering if we damage the LMG3522 device, although, our load is well below the specs of the device.

Is there anything else we can try to solve the issue?  

Thank you!

Thanks for sharing the details.

Please look into the following basic tests to identify the problem. If these steps still do not resolve the issue, we can investigate further.

• Removal of VDD should RESET the FAULT if it is created from a short condition. If you see the FAULT signal after VDD RESET please check for a HV+ to PGND short on the board before powering it up.
• Check VDD at the GaN pin to confirm that it’s not entering UVLO
• If you are able to power up then please try providing the PWM signal from an external PWM generator instead of the control card and check if the EVM + motherboard functions for a basic buck operation.

Please describe the nature of the load. Is it a capacitive load with some Voltage source in series? In case of capacitive load, the peak pulse currents might be reaching high which might be source of FAULT in your test. Can you share some waveform of the load current. Also what are the input DC voltage levels for the test.

Thanks,

Subhransu