DC/DC solution for +-15V from 9-12V DC input

[belzrebuth]

Hi all,
I need to have a bipolar supply from a 9-12V source. up to 80mA output at each rail of the bipolar supply (maybe even less) is required.
I've tried a TRACO TBA 2-1223 which fit the bill on paper but I was getting some ground hum at the output.
I could try the bigger version TEC 3-0923 but I am already thinking this could get far more expensive than using a DC/DC converter IC and some passives.
I've looked at various boards from aliexpress that have one or two chips and passives so ideally I'd like to do the same on my board but use a chip I can get from a reputable source like the TPS5430 or similar but I didn't seem to find any simple solution online for my application.
I surely must be missing something..

[CountChocula]

What's your use case? The TBA 2-1223 has an unregulated output—that's probably why you were getting those strange results.

If you want an off-the-shelf solution there are several (like this one) that might fit the bill. You will want something that's regulated; the reason why I'm asking for the use case is that the ripple out of one of these modules (typically in the 10s of mVpp) may not be appropriate for your needs.

If you want to go a more discrete route, there are a couple possibilities: boost your positive voltage up to +15V, then use a charge pump to generate a -15V rail (though this will usually only be good up to ~10mA, and you will still have to contend with significant ripple). Alternatively, look up “rail splitter” circuits; you boost your input voltage to 2x Vout (so, 30V in your case), and then create a new virtual ground at 15V, giving you both rails. These can be a little complex, but they can also be made to source significant amounts of current.


—CC

[rstofer]

Murata makes a lot of bipolar output DC-DC converters.  Here's the Product Search page.  Your input voltage may be too low for the devices I have seen but I've only looked at a couple

https://www.murata.com/en-us/search/productsearch

[Benta]

Use a Traco type with regulated outputs.