Input: -24V DC; Output: 5V, 100mA

Hello Bell,

 If you go to the TI Reference Designs: http://www.ti.com/power-management/reference-designs.html , the closest design we have is an inverting buck-boost PMP20371: http://www.ti.com/tool/PMP20371 .

This could be a good start; you would have to take the design concepts and change to match your requirements.

I will also look for any other solutions we might have.  Let me know if you can work from this PMP20371 design.

~Leonard 

  

Hi Leonard ,

Thanks a lot for your answer. this seems to be a good solution. I will check with customer and feedback you later.

regards,
Bell

Hi Leonard ,

Thanks for the feedback. we also have considered this topology like below. While, the only concern is that: the output 5V (actual 29V) is reference to the -24V input. When the input -24V is not stable (there can be some fluctuation), the output 5V can also have a 1:1 change. this can be a big problem.

Do you have any idea to solve this problem? thanks!

regards,

Bell

Bell,

Please look at the following reference design. The TPS40210 is utilized and transforms -12V to +12V @1A. This might be a good starting point for our application.
www.ti.com/.../PMP4742

More reference designs can be found on the TI Designs website.
www.ti.com/.../refdesignsearchresults.tsp

Thanks,

Garrett