Power Supply Recommendation is needed: DC-DC 20v to 12v 130W (or 2 x 70W)

[abrilevskiy]

Hello,

Could you please recommend DC-DC convertor of 20v to 12v with 130W power (or 2 x 70W). I would like to use USB-C power supply (with Power Delivery trigger 20v) to power RTX 3050 (130W max).

Thanks you!

 

[msystems]

Do you mean using it in tandem with one of the Usb-pd wall bricks? The Usb-c pd controller chip might not like the implementation because they have a strict amperage limit. Even with a 240w rated usb-c pd cable and proper "e-mark" 5a pd trigger it might cut out well before the rated wattage. If you have saw someone that had success doing this to a gpu or sffpc can you please share it? I'm very interested in seeing this done successfully.

For dc-dc PSU you can take a look at Pico Box and rGeek. They come in different ratings from 75w up to 300w and you need a usb-c to dc-barrel cable with integrated 5a 20v trigger.

https://www.aliexpress.us/item/2255800035602000.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US

 

[abrilevskiy]

Do you mean using it in tandem with one of the Usb-pd wall bricks?

Yes, You are right

Even with a 240w rated usb-c pd cable and proper "e-mark" 5a pd trigger it might cut out well before the rated wattage.

It looks like I faced the issue in the past - do you know why it happens - sound strange to me: if PSU rated to provide 20v & 5A and I consume 20v and 4A - why PSU would cut out at this stage?

If you have saw someone that had success doing this to a gpu or sffpc can you please share it? I'm very interested in seeing this done successfully.

I saw a person who posted that his next step will be to try using PD power supply, but it was a quite a while ago without new post and results.

For dc-dc PSU you can take a look at Pico Box and rGeek. They come in different ratings from 75w up to 300w and you need a usb-c to dc-barrel cable with integrated 5a 20v trigger.

I reviewed PicoBox and see that they provides full set of ATX power +5v, +3.3v, -12v that makes PSU more expensive.
I found the following:

• https://www.meanwell.com/webapp/product/search.aspx?prod=NID100
• https://www.mouser.pl/datasheet/2/281/1/mures33042_1-2277594.pdf
• https://www.murata.com/products/productdata/8807036256286/mysgk02506brsr.pdf

 

[msystems]

It looks like I faced the issue in the past - do you know why it happens - sound strange to me: if PSU rated to provide 20v & 5A and I consume 20v and 4A - why PSU would cut out at this stage?

I dont know why for sure, but it has a microprocessor constantly monitoring the current and voltage. It seems like USB-pd chips are supposed to monitor and enforce load curves, because batteries need to be charged a certain way for maximum life.

I find this diagram on page 40 of Battery Charging Specification rev 1.2. Maybe there's some things in there that could explain it as there are lot of conditions and logic the charger is following.

Battery Charging v1.2 Spec and Adopters Agreement | USB-IF

www.usb.org

 

[abrilevskiy]

I noticed that this project uses USB-C power delivery: https://smallformfactor.net/forum/threads/pocket-egpu-a-0-55l-thunderbolt-rx6400-pocket-egpu.17582/

 

[msystems]

Yes, thats true it seems to be working well for that project. I think you should try your idea, and report if it works and all the parts you used.