• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 64 subscribers
  • Views 779 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

+/- 12V rail from 30V Hi-temp

Benjamin Couture
Prodigy 140 points
Other Parts Discussed in Thread: TPS40200-HT, TPS54362-HT

Hi,

Here is are some of the spec of what I need to build;

Input: 24 to 32

Output: +/- 12V @ 250mA

Ambient temperature: 150C to 175C

Application : Down hole oil drilling

I read a few post about making an inverting buck step down converter. I noticed that some of the IC are featured as inverting buck, but not those for temperatures above 150C. So I wonder if the inverting buck applies to any buck converter or if it's only certain of those that has that capability. If it's only certain of those that can, what are the specs that I have to look for to ensure that it does.

Thank You,

Ben

  • 0
    TI__Guru**** 191445 points

    You are going to have a tough time with that temperature spec.  I do not think even space qualified parts are rated for that.  For most of our parts 150 C ambient means zero power dissipation as 150 C. is the maximum junction temperature for operation (even mil spec is usually only rated for 125 C junction temp).  I suspect you may have to build that from discreet components or possibly provide for some type of active cooling.

  • 0 in reply to JohnTucker
    Prodigy 140 points

    Thanks for your answer,

    Some of your device are 175C and 210C rated, here are the two that I had interest in: 

    TPS40200-HT 175C (integrated switch)
    TPS54362-HT 175C and 210C (external switch)

    Basicly, I wanted to know if I could make an inverted converter with those or not. Right now the only alternatives that I found was some cissoid devices. They are very high temperature rated but doesn't shine much in efficiency. Texasmicroelectronics makes some P.S. dual rails with those IC, but they get only an efficiency of 65%. This become an issue not only for the down hole battery waste but also for the heat dissipation along with other aspect of their devices that doesn't perfectly match our needs.

    Thank you again for your quick help

    Ben

  • 0 in reply to Benjamin Couture
    TI__Guru**** 191445 points

    Yes you might be able to do that with TPS40200-HT.  Withe the inverting buck-boost and coupled inductor you can make a dual supply.  You will have to watch the peak currents as they will be higher than the output current.  Efficiency will depend on what FETs you can find.  There probably aren't any simulation tools for that app, so you will probably need to make a prototype to test.