| Electronics > Beginners |
| Generating +15/-15VDC with a single boost converter |
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| ratatax:
Hello For powering the opamps on my projects i need +15/-15 V from a wide DC input range (let's say 8V...16V). I found those modules on ebay : https://www.ebay.co.uk/itm/15V-Positive-Negative-Dual-DC-DC-Step-up-Boost-Converter-Module-3-3V-5V-12V-/172763714588 I'd like to design this thing on my circuit, but they sanded the chip (duh!). Does anyone knows how they create the double voltage from a single buck converter ? I guess it's a single-rail stepdown/boost converter since it uses only one inductor. It uses three big output diodes, which may give some informations for experienced people designing power supplies, but unfortunately i'm not in this domain at all... Searching for dual converter schematics on the net doesn't give much results.. any idea ? |
| iMo:
I did negative voltage such I wired 2 diodes and 2 capacitors (a voltage doubler) to the node where the inductor is wired to the original diode. It seems The above module is doing that the same way. |
| Rerouter:
Not as cheap, but at a starting point there are drop in modules that will work, and give you an actually specification you can trust in how much current and noise you can expect, https://au.mouser.com/Power/DC-DC-Converters/_/N-brvxe?P=1yx5k7uZ1yxt6orZ1yxt6peZ1yxt7erZ1yxt78xZ1yxt6phZ1yo7fn8Z1yxt7cyZ1yxt74mZ1yxt78nZ1y9oph1Z1yxt6pfZ1yxt7dyZ1yxt793Z1z0k0eqZ1yzxopsZ1z0k0enZ1z0k0epZ1yztqpbZ1yqwpv0Z1z0k0eiZ1z0wavnZ1yqwpgk&Ns=Pricing%7c0 They start at about $14 AUD from where I have found them, As for the exact chip they are using in that module, hard to say, most regulator IC websites have some level of parametric search, Texas Instruments atleast the last time I went looking even had a wizard to spit out the exact schematic for a given problem with a BOM and everything. you would be looking for a chip that does +- output, most of them will not be rated at exactly +-15V, that just happens to be the feedback divider they chose. |
| ratatax:
Thanks for this schematic that's quite an elegant solution ! For an integrated DC-DC module I found cheaper on LCSC : https://lcsc.com/product-detail/Power-Modules_Guangzhou-Aipu-Elec-Tech-KW3-05D15E3_C232043.html 3W regulated, 4.5/9Vin, +/-15V out, $5. But I need to think a bit, designing it myself would be cheaper, with more readily available parts and you know exactly which components you use. |
| iMo:
It is maybe an elegant solution but you have to understand the limits too. The -V is not "regulated" and usually "weak". It means it never will be exactly -15V, and with larger loads than a couple of mAmps the voltage will drop down. As I've written above, the module in your first post is doing that -V the same way, therefore if you happy with that module you may use the "elegant" solution, indeed :) |
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