LM5116: Powering LM5116 from external LDO

Aidan Phillips

Part Number: LM5116

Is there any issue with powering the LM5116 from an LDO such that the voltage going to the power stage (drain of high side FET) is higher than the voltage powering the Vin pin of the chip?

I wouldn't think this would be an issue as there is an LDO internal to the IC anyway, but wanted to see if there are any gotchas here.

over 3 years ago

0 EricLee over 3 years ago

TI__Guru 59001 points

Hello Aidan

Thanks for choosing TI. Please refer the answer of this LM5116 E2E post.

Eric Lee (Applications Engineering)

0 Aidan Phillips over 3 years ago in reply to EricLee

Prodigy 140 points

Hi Eric,

Just to clarify the "Pwr Vin" mentioned in this post is just the Vin pin on the IC? (Pin 1)

0 EricLee over 3 years ago in reply to Aidan Phillips

TI__Guru 59001 points

Hello Aidan

In that E2E post, 'Pwr VIN' is the input of the buck converter, not the VIN pin of the IC

- Eric Lee (Applications Engineering)

0 Aidan Phillips over 3 years ago in reply to EricLee

Prodigy 140 points

Ok so when it is said that "Note that it is preferable to connect the actual pwr input supply voltage (60V) to the controller as this results in correct line feedforward behavior and emulated current ramp slope ", The recommendation is to connect Pwr VIN to the Vin (pin 1) of the controller, or to VCCX?

0 EricLee over 3 years ago in reply to Aidan Phillips

TI__Guru 59001 points

Hello Aidan

The recommendation is to connect the input of the buck converter to the VIN pin of LM5116, not the VCCX pin of LM5116.

- Eric Lee ( Application Engineering)

0 EricLee over 3 years ago in reply to EricLee

TI__Guru 59001 points

Hello
I am closing this thread since I have not heard from you for sometime.
If you are still trying to resolve the issue, please feel free to open a new thread or reopen this thread. Thanks
- Eric Lee (Applications Engineering)

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LM5116: Powering LM5116 from external LDO