SM72295: SM72295 HOA,LOA waveform issue

Hsu cheng

Part Number: SM72295

The waveform I measured from my customer's board is as follows. Is there a way to solve the low voltage level of the HOA waveform?

Does this waveform cause Hihg low side MOSFET short circuit?

0 Jeffrey Mueller over 5 years ago

Hi Hsu,

can you show me the portion of the sch including sm72295 and fets?

HOA is yellow? LOA is blue? why does the yellow waveform not go to ground? are the two probes wrt driver PGND pin?

-HO should be going from Vbus+Vdrive all the way down to 0v when the lowside turns on (assuming this is half bridge config)

-is the highside fet turning on/off?

I dont see a short happening since theres good deadtime. but can we look at the half bridge leg current to see if there is shoot though.

Thanks,

0 Hsu cheng over 5 years ago in reply to Jeffrey Mueller

Expert 1565 points

HOA is YELLOW,LOA is blue, the two probes wrt driver PGND pin, the sch follow as,Is there any solution for reference?

0 Jeffrey Mueller over 5 years ago in reply to Hsu cheng

Thanks Hsu,

Is this a reference design from ti.com? is the application for mppt solar charger?

Can we observe what the switch node is doing at the same time as HOA/LOA? I would like to see if HS-PGND is going to 0V during lowside on time.

Its possible that the snubber is holding the switch node above 0V. whats the load current? whats the input voltage output voltage and frequency?

Thanks,

0 Hsu cheng over 5 years ago in reply to Jeffrey Mueller

Expert 1565 points

Yes, this Circuit is a reference design for TI reference deisgn,Currently testing under no-load conditions.

0 Jeffrey Mueller over 5 years ago in reply to Hsu cheng

Whats the reference design called?

Are you able to take a scope shot of the switch node along with the outputs as requested in my last post?

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