UCC38085: What doesVbat means in the Webench Design?

Art Mecina

Part Number: UCC38085

Hello Guys,

Good day.

Our customer just like to clarify what the the voltage source Vbat that is connected to the Vdd pin of UCC38085 means. Is this a battery? What type of battery is this?. See below image.

Thanks for the clarification!

Art

over 4 years ago

0 Hong Huang over 4 years ago

TI__Guru 73265 points

Hi,

Where did you get that portion of circuit? Can you provide the full schematics so to understand why a battery is used?

0 Art Mecina over 4 years ago in reply to Hong Huang

TI__Genius 16655 points

Hello Hong,

Apologies for the delayed response as I have to confirm first with the customer if the schematic can be shared here. Refer to below link for the full schematic.

https://webench.ti.com/power-designer/switching-regulator/customize/86

Thanks!

Art

0 Hong Huang over 4 years ago in reply to Art Mecina

TI__Guru 73265 points

Hi,

Where is Vbat in your provided circuit?

0 Art Mecina over 4 years ago in reply to Hong Huang

TI__Genius 16655 points

Hi Hong,

I have attached the schematic in pdf.

The VBAT is the one connected to Vdd pin of U1 (UCC38085D).

UCC38085.pdf

Thanks!

Art

0 Art Mecina over 4 years ago in reply to Art Mecina

TI__Genius 16655 points

Hi Hong,

I might direct the customer to this thread so that he can explain his use case better.

Best regards,

Art

0 Hong Huang over 4 years ago in reply to Art Mecina

TI__Guru 73265 points

Hi,

That is just to show a bias is needed for UCC38085. The bias circuit is not designed so a battery is shown here to say here a bias is needed and you need design a bias. A usual way is to add a bias winding to the transformer to serve this purpose. But the circuit you provided does not have such a bias so the circuit uses a battery to represent this bias.

0 Till Heuer over 4 years ago in reply to Hong Huang

Prodigy 20 points

Hi Hong,

thanks for your answer.

I was already thinking that the ic's need a bias voltage, but I wonder how high this voltage must be.

Kind regards

Till Heuer

0 Hong Huang over 4 years ago in reply to Till Heuer

TI__Guru 73265 points

Hi,

You can find these in the datasheet, page 3.

0 Till Heuer over 4 years ago in reply to Hong Huang

Prodigy 20 points

Oh ok, so I have to power it with an 10V aux winding.

Thanks a lot!

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UCC38085: What doesVbat means in the Webench Design?