Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


PFC Power Supply VCC

PFC Power Supply VCC

PFC Power Supply VCC

I am designing a SMPS with a PFC correction circuit and then a 390V to 24 V DC-DC converter. Both the PFC chip and the DC-DC converter chip require a 12v VCC. Any suggestions for a circuit? I was thinking of using a resistor and a cap with a clamp after the diode bridge, but it is about 30 mA and that would be quite a bit of wasted power. Another option would be a flyback converter. Would running this off the Diode Bridge mess with the PFC? Any suggestions?

RE: PFC Power Supply VCC

Searching with the keyword 'bootstrap' (in addition to more obvious terms such as SMPS) brings up plenty of ideas.

TI app note SLYT077:
A better bootstrap/bias supply circuit (PDF)

2005, so perhaps a bit old. But seems to still be valid.

That's just an example. Plenty of others.

RE: PFC Power Supply VCC

Special IC...

Supertex LR745 (PDF)

Appears to be an attractive approach.

Good luck.

RE: PFC Power Supply VCC

Thank you VEIBLL! Very good ideas and suggestions. The LR745 looks promising

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now
White Paper - Analysis and Simulation in Aircraft Structure Certification
Organizations using simulation and analysis tools effectively see the benefits in their ability to achieve certification faster and with drastically less total cost than those who do not maximize these tools. Read this White Paper to learn about how digital tools such as analysis and simulation help in aircraft structure certification. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close