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

Switching center

Switching center

Switching center

I have an input voltage at 48-54VDC and I would like to convert that to +/- 24-27 VDC.
The currents involved in either or both voltages can be anywhere from 0-3.5 Amps.(I.e. the currents are not always the same in both channels)

A standard OP-Amp controled linear power stage can do it, but I find the power loss too great.

Does anybody know how to make a switcher, that can do it ?


RE: Switching center

Noise is not that big an issue.

The main users on the dual voltage system will be electromagnetic devices, so say 1 V ripple should be acceptable.

In the meantime I have so far come up with 2 possible solutions on my own.

A totem-pole driver switching the 50V at 50% duty-cycle and then an LC-filter to the center "0V"

Switching the 50V down/up to +/- 4V from the "0V" center and do it linear from there.

RE: Switching center

If it is for EM devices, you can use the 50% duty cycle
squarewave directly -- no filtering is needed.
If the frequency is high enough, you can have very
low current ripple value.

You don't need totem-pole -- one-sided switch is OK.


RE: Switching center

As I will need to both sink and source current through the center line, I still think a totem-pole drive is in order.

Also some sort of a filter is in order, as I will have fairly long connections to the various devices.
(radio noise from the wires)

RE: Switching center

You will get an very effiecient solution when you use a charge pump design. Take a look at the opeation of one of the numerous charge pump ICs and try to design a circuit operating in the same way at the power level you need using discrete Mosfets.

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


Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now
eBook - Managing the Context of Product Complexity Using the Digital Twin
Keeping track of changes to complex products is difficult—think Aerospace & Defense equipment, new generations of commercial aircraft, and software-based automobiles. A new way to managing the digital context of the physical product is required and the answer is the Digital Twin. This ebook explores the opportunity available for Operations and Maintenance for the Digital Twin. Download Now
White Paper - Trends in Industrial Filtration
Substantial progress has been made in filtration technologies in recent years. New filter media materials, designs and processes have led to filters that are more efficient, reliable, compact and longer lasting. This white paper will discuss the various trends that are impacting operational responsibilities of MROs today and the resources that are available for staying up-to-date on the latest filtration solutions. 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