LM5176: LM5176PWPR

william myntti

Part Number: LM5176

The four MOSFETs that make up the H bridge driving the Inductor are coming on at the same time and some MOSFETs gates are not reaching 0V. Both the right and left side of the H bridge are on at the same time and both the top and bottom fets are on at the same time.

Looking at Q23 yellow (top right of H bridge) and Q25 purple (bottom right of H bridge)

Lookling at Q24 purple (Top left of H bridge) and Q26 yellow (bottom left of H bridge)

over 4 years ago

0 Brigitte over 4 years ago

TI__Guru 65470 points

Hello William,

Please measure the gate signals on the LM5176 directly. Which input and output voltages do you have at thiese measurements?

3.5V is very low for the driver signals, which voltages doe you have at VIN, BIAS and VCC?

Best regards,
Brigitte

0 william myntti over 4 years ago in reply to Brigitte

Prodigy 10 points

With a board supply input of 36Vdc

Vin= 33.5Vdc

Vbias= 0.15V

Vcc = 3.66V

Gate voltages did not change.

0 william myntti over 4 years ago

Prodigy 10 points

Pin 1 EN/UVLO is 6.6V

0 Brigitte over 4 years ago in reply to william myntti

TI__Guru 65470 points

Hello William,

With a board supply of 36V, VCC should be in the range of 7.5V, please check the input voltage directly on the IC. Either the input voltage does not reach the device or the device got somehow damaged.

Best regards,
Brigitte

0 Brigitte over 4 years ago in reply to Brigitte

TI__Guru 65470 points

Hello William,

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

Best regards,
Brigitte

0 william myntti over 4 years ago

Prodigy 10 points

Please see answers below on VCC. Would like to know what could have damaged paret if that is indeed what happened. We do not have a 12V regulator solution right now and are uncomfortable going forward with anouther Ti switcher.

0 Brigitte over 4 years ago in reply to william myntti

TI__Guru 65470 points

Hello William,

I am sorry that you have issues with the LM5176. I do not find information on VCC and as I do not know how the device is damaged, I cannot guess what was happening.

Would you please share your schematic? Then I can check it out.

Best regards,
Brigitte

0 william myntti over 4 years ago in reply to Brigitte

Prodigy 10 points

With a board supply input of 36Vdc

Vin= 33.5Vdc

Vbias= 0.15V

Vcc = 3.66V

Gate voltages did not change.

0 Brigitte over 4 years ago in reply to william myntti

TI__Guru 65470 points

Hello William,

With an VIN of 33.5V, the VCC needs to be in regulation, see Figure 4 in the datasheet.

If this is not the case, either there is a lot of current drawn from the internal regulator which the regulator is not able to apply or the device is damaged. Please replace the device or check another board.

Best regards,
Brigitte

0 Brigitte over 4 years ago in reply to Brigitte

TI__Guru 65470 points

Hello William,

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

Best regards,
Brigitte

Power management

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LM5176: LM5176PWPR