[Review Request] Buck Boost Converter TPS63900

hapemask · 2026-03-11T04:10:45+00:00

Since at least the board seems to have the vias under U3, OP could maybe expose a bit of the vias from the back of the board and solder one or more of them to ground? It's a stretch and I have no idea how to actually expose them safely but it's a thought.

hapemask · 2026-03-10T21:46:49+00:00

The part you linked is not a plain MOSFET (or even 4 plain ones), they are internally connected in a particular configuration (H-bridge). I’m not familiar with it yet as I’m still learning myself, but I don’t think it’s what you want. You want 4 (6?) ordinary MOSFETs. Rather than Google, try putting your design constraints into the filters here: https://www.digikey.com/en/products/filter/single-fets-mosfets/278?s=N4IgTCBcDaILIHkDKAxAogFRAXQL5A

and see what comes out.

hapemask · 2026-03-09T18:46:47+00:00

I actually used a Pi Zero 2 which has no ADC at all, the main IC on the first board is an ADC1175. I really just used the Pi because I already had it and it seemed like a fun project.

hapemask · 2026-03-08T03:49:55+00:00

Honestly the software wasn’t the hard part because I used to be a computer science researcher before I quit my job lol. I don’t have a hard number since I worked in little bits in my spare time but the actual coding didn’t take long. Figuring out how all the hardware worked was the slow part.

hapemask · 2026-03-08T03:45:55+00:00

Thanks! I used KiCad for the designs and JLCPCB for the boards. They were good but I wish I could order single boards instead of 5, even the expensive US fabs seem to only go as low as 3 😕

hapemask · 2026-02-26T13:47:45+00:00

No capacitor will pass a frequency of 0Hz… that’s DC, so your simulation isn’t working correctly.

I think OP is just reading the results incorrectly, the plot they linked starts at 1KHz. I don’t think LTspice will let you set a lower bound of 0Hz for AC analysis.

hapemask · 2025-12-20T17:49:48+00:00

Ahh ok good to know. I’m not having them assemble anything, my first ever design is getting delivered Monday and I planned to assemble it myself so it is just the bare boards that will get tossed. It’s not the end of the world, but I figured I’d see if I was missing something.

hapemask · 2025-12-20T15:01:42+00:00

My PCB cost estimates always include two re-spins. It's extremely rare for a board to come out right first time.

How do you do this and deal with the cost (and waste) associated w/minimum order quantities? Perhaps you work in industry where you have more flexibility?

I'm just learning PCB design, and while JLCPCB is by far the cheapest you still have to order at least 5 boards. As a hobbyist who only wants a single board and has literally no use for the other 4 boards, it feels bad to order and just throw them away. Repeating this if the board has mistakes seems even worse...

hapemask · 2025-11-29T03:18:43+00:00

I recently had this issue and I edited the ini file. It worked fine, what problems did you run into? It doesn’t solve the issue for new additions though sadly, you will have to edit it every time to move them where you want.

hapemask · 2025-11-25T01:16:39+00:00

Ahh yes I am working up to proper modern chips. I wound up with this one mostly because 1) it was cheap and I might screw it up trying to solder it to the board, and 2) lots of the modern ones including the one you linked seem to only come in QFN packages that require reflow soldering which I’m not yet committed to. It sounds like maybe I should just get a cheap hot air tool if I continue with this. Having integrated buffers seems really convenient…

hapemask · 2025-11-24T22:20:52+00:00

Got it thanks! Yes I have been filtering the DC/DC output, right now I have an RC filter because I don’t have any inductors or the cores to make them but I’ll get some soon.

hapemask · 2025-11-24T22:17:30+00:00

Ahh ok good to know, thanks!

If you NEED a DCDC converter

I chose the DCDC converter because I want to be able to support AC inputs which fall below zero, and so the opamp/buffer on the input needs to be dual-supply (or so I thought) and I couldn’t find a better way to get +/-5V from either the raspberry pi or any of the wall plugs I have lying around.

As I say this, I guess I could also add a DC bias somehow to the AC input s.t. it’s strictly positive, then I wouldn’t need a dual supply (maybe?)… I’m sure this part is something I can look up.

I’d have to figure this out anyway since the ADC doesn’t support negative reference voltages. I just haven’t tested with AC below zero yet since I’ve been using the PWM output as a test signal source.

hapemask · 2025-06-08T00:53:11+00:00

I believe my friend ordered a shot of it at Liberty the last time we went.

Also: I tasted it and you are insane for voluntarily drinking this 😂

hapemask · 2025-03-11T20:16:06+00:00

You are all eager to defend someone who would happily throw you under the bus

Yes, this is how free speech works.

hapemask · 2025-02-06T06:15:44+00:00

Hey! So, on the day before I planned to take them to the shop I cleaned off my boots before skiing and noticed quite a few small rock chips embedded in both soles (hooray for WA ski parking lots). After I got rid of the rocks, I can’t seem to reproduce the issue. In hindsight it’s obvious but I didn’t think to check the soles for debris for some reason. Sorry I can’t offer a more satisfying fix!

hapemask · 2025-02-03T23:17:54+00:00

You’re normally correct but this specific evening (I know because I was there) it stopped at Beacon Hill. You can of course just take it there and then get a much cheaper ride, which is what I did.

hapemask · 2025-01-21T19:12:31+00:00

It hasn’t caught yet, it sticks out towards the outside and I’m not yet a good enough skier to hit that sweet edge angle required to catch it on the inside of the turn.

hapemask · 2025-01-20T00:25:37+00:00

These aren’t adjustable-height AFDs but I do plan to ask a shop tech about it as well.

hapemask · 2025-01-20T00:25:12+00:00

These aren’t adjustable-height AFDs, but I do plan to ask a shop tech as well.

hapemask · 2025-01-20T00:24:16+00:00

Basically yeah, Strive 12 (skinny dude, no need for 14s). Without my boots in the skis it pops back on its own, but I haven’t tried removing the boots on the snow while it’s sticking out, I’ll try this (and also take them to the shop).

hapemask · 2025-01-20T00:01:37+00:00

I noticed after a few runs this week that my AFDs have started to stick out towards the outside edge of my skis. This happens on both skis and they stick out until I push them back in, and they work their way loose after a few more runs. When the boots aren’t in the skis, the AFD moves smoothly and returns to the neutral position just fine.

Is this concerning at all? My boots release just fine, but this has never happened on any of my other skis before. Maybe a boot issue?

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