LMG3422EVM-043: LMG3422EVM-043

Ronald Musona

Part Number: LMG3422EVM-043

I am trying to test the GaN daughter body (LMG3422EVM-043) as a synchronous buck. Around 350V input, If I increase the load current close to 10A, it tripes. (a fault on the upper MOSFET). Any help on what could be causing this is appreciated.

6 months ago

0 Kyle Wolf 6 months ago

TI__Expert 5385 points

Hi Ronald,

Can you share more details about your setup for the buck converter, what are you connecting the GaN daughter card to? How are you controlling the PWM input to the daughtercard and how are you reading the /Fault, /OC pins from the daughtercard?

Best,
Kyle Wolf

0 Ronald Musona 6 months ago in reply to Kyle Wolf

Prodigy 10 points

I am supplying the DC source 350V directly to the daughter board(PGND and HV). The midpoint pin of the daughter board (SW pin) is connected through an LC filter to a resistive load. The PWM signals are being supplied by a DSpace controller for the high side and low side MOSFETs( HS_PWM and AGND and also LS_PWM and AGND). I am increasing the current by increasing the duty cycle of PWM signals, at some point around 9Amp output current, it is tripping(i.e the midpoint SW voltage pulses that I am reading on the oscilloscope stops displaying). Iam reading the fault on pins(HS_Fault and LS_fault which are active low).

0 Ronald Musona 6 months ago in reply to Ronald Musona

Prodigy 10 points

In addition, I am powering the daughter board with 5V from the DSpace controller, and a deatime of 100ns.

0 Kyle Wolf 6 months ago in reply to Ronald Musona

TI__Expert 5385 points

Hi Ronald,

This sounds like the GaN FETs are registering a /Fault condition. Are you also monitoring the /OC pin in this test?

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LMG3422EVM-043: LMG3422EVM-043