Yep, Thatās a great one to remember. I find whenever I am avoiding writing code or doing something with RF (my two current learning vectors), itās because I afraid of looking stupid and/or having to put in the work.
Iām currently in the direction of building modules to help create reusable designs for future projects. I saw a lot of stuff relating to EMI in DCDC converts. For something like this project should it matter? Like to know whats everyoneās thoughts are.
The other day I was thinking it would be cool if I could design something for our horses. Something like filling up the water buckets until said level and control it through my phone lol
You know at 2uA, there are probably a few photons coming outā¦but yeah, youād need to start building photomultipliers to detect them
Great looking design! And I like that you are building up the reusable modules.
As for EMI, the biggest sources are going to be from not having a tight āloopā between the switch pins on the chip and the inductor. If youāre following the recommended layout, youāll probably solve 80% of the problems. After that it will come down to the inductor shielding (if present) and any other place where current canāt get to where it wants to go.
Thank you for everyoneās input! Gave me some thoughts to research on.
Good to know Chris! Felt like I reread the datasheet a bunch of times to make sure everything was good and eval board user guide really helped out as well.
My whole BOM is built around Digikey at the moment. I figure I would get a few of them made over at JLCPCB, solder them up here then see how they play.
The Inductor of choice is SRN5020TA-120M. Since its 600mA Max circuit and 1.4A rated inductor which to me should be no problem but when I was playing around on TI Webench I notice it allowing me to pick an inductor with current ranging all the way up to +4A ex. MSS1038-123MLB. Also notice that DCR was a lot lower with coils with higher current ratings.
So really whatās stopping me from choosing something like that aside from cost and size?
As far as test equipment goes, I lean towards the microcontroller world and been playing with the stm32 Nucleo board. I currently only have DMM, bench power supply, soldering station, and hot air station. An oscilloscope and or logic analyzer is on my radar but likes to know what you guys recommend or add to the list of must-have.
For RF related stuff, A guy I work with is huge into RF and has a ham radio license and as interesting as it sounds when he talks to me about it, it goes over my head or smoke comes out of my ears haha.
Sure, you can use the bigger inductor. Penalty is cost and size as you wrote
Benefit is better efficiency, lower loss, lower thermal hot spots
For a bigger core, the flux density falls. Losses is about B uplifted to 1.7, so lower B field, a lot lower losses. Losses can be calculated from here:
Hello everyone! Wanted to provide an update on my first dcdc module. It works!
When I placed my order with JLCPCB provide my Gerber and stencil to be 39x39mm. The very next day, I received an email that the audit failed and examples to me Iām missing the NC drill files in the Gerber. Fair enough and fixed that right away.
Good idea on the tin snips! I always try to just use the entire thing and I get alignment issues. Then again, I have cut myself on stainless steel stencils (nasty slices) that Iām pretty careful around them in general.
Board looks great! I am curious about the iron as well
What you guys didnāt see is when I first upset the iron, it tipped over and the board fell into the carpet haha. To my surprise, all the 0402 components were still on the board!! Few books later, I made the support for the iron. Definitely need a vise for this lol.
I guess I can say I reflowed the board base on āfeelā started at the lowest temp and slowly ramping it up with the clothes iron then got my hot air gun set to 230c @ lowest airflow. Didnāt want anything flying off haha. For next time, recently bought a temp probe to get a better idea of what the temps are when Iām reflowing the next board.
In the past, Iāve reworked many SMT boards with hot air guns as well as bottom plate heater. Reading a datasheet that talks about the reworking process really helped me understand the process and seeing how manufacturers do it. When I first started out, it was trial by fire! Iāve burnt a lot of stuff by testing it on with E-scrap we had laying around. All in all, I learned a lot by just jumping in, and who doesnāt like the smell of a burnt PCB once in a while lol.
The iron idea is excellent. I might have to try that. Iām sure thereās an iron around here somewhere, and Iām sure no-one would mind if I used it for reflowing some boardsā¦
Can you remember what it was that you read about SMT rework that was so useful?
I remember first seeing it in a manual that came with this BGA rework machine. Spoke about temperature profiles, how to set them up, and showed a profile chart.
We mostly could get by with air gun and or heat plate but when we needed to remove something complex without pulling pads to the BGA machine. Oh I tried for laughs to remove a processor with 529 pins on 8 layer board. 400c @ max airflow and 5ish minutes later. It was not the best letās just say lol.
As far Iām aware, many manufacturers follow IPC-7530 standard when it goes through SMT assembly.
Hope everyone has been enjoying the holidays and staying safe out there. Just wanted to pop in and share a wip project. In a nutshell, it locks a door. There is a mainboard behind the scenes that will talk to this device via RS485. Here the top-level of the project so far.
Going to slap in MAX or SP3072E and bobās my uncle! haha. RS485 is still a bit new to me.
The wire is coming off the RJ50 jack going down about 6ft to the door. The RJ50 jack supply +12V, 5V, +/-485 signals. The door has 2 switches, which will tell me if the said door has been opened and if the box has been removed. IR sensors to tell me what state the lock is in to provide feedback to MCU to let me know what position itās in but in the event, if the sensors were to fail then flag us and put the MCU into limp mode so things remain locked. If the lock board failsā¦wellā¦time to get the blow torch haha
Iāve been pondering about building my own door lock system 'cause I donāt trust any of the commercial onesā¦ Can you describe your use-case a little and what the mechanical hardware looks like?