WEBENCH® Tools/LM5176: LM5176 Pin19 HDRV2 no driver signal

Hello user4332422,

Please share your schematic and your input voltage range.

BTW, it is strange that there is some oscillation on the yellow signal. Where does this come from?

Please measure the SW pins as well.

3531.LM5176.pdf

when I rise input voltage to 16V, the waveform as below shown:

Hello user4332422,

Is it possible that the load current is very low at your VIN = 16V input measurement? Is this again the drive signals? Please measure the switch nodes.

Please measure the output voltage and check if it is correct.

Yes, it's drive signals with 4A load. The unit can handle 25A load and output voltage is correct. Only HDRV2 no driver signal and high side Mosfet too hot.

Hello user4332422,

Did you try to exchange the IC already?

Can you please check if the transistor connected to HDRV2 is still working properly?

I checked 2 PCBA, both phenomenon the same. And this HDRV2 can work normally during buck condition.  

Hello user4332422,

The schematic you attached is not the full schematic. Please attach the full schematic.

Please check if it helps to add gate resistors in the range of 5 ohm.

Hi Brigitte,

I changed driver resistors to 3.3R and tested unit:

Vin 10V， Vo 15V，Io 5A.

The HDRV2 only give 120nS driver signal, I don't know where can turn off this driver. CH1: SW2, CH2:BOOT2, CH3:HDRV2, and purple is Math(CH3-CH1) means boost converter high side Mosfet driver. Do you have any commets?

Hello user4332422,

As I did not hear back from you, I expect that you have been able to solve your issue and will close this thread now. If this is not the case, please post below or create a new thread if this one is already locked.