My MYSX Multisensors board
-
@carlierd: merci :)
Last night, I made some change from previous feedback ;)
- 2 versions :
- my preferred stepup version (not friendly because of the tiny stepup like I said)
- a buck version. But an interesting one, and of course it is better to use with lithium than classic lipo&co (sefldischarge...)... But in case, some people would be disappointed by inaccessibility of the stepup rev, I have done this new one. For 3 or 4 primary AA/AAA cells, or other setup... Before, when I was seeing lot of cells in a device, I was thinking "what a battery eater!!". But now I am thinking different, it can be justified in case the device is low power ;) So it is an alternative, why not.
- 0805 passives on two version (but for the stepup passives, I keep 0603 around it, shorter routes)
So which buck I choosed?? I could have choosed some dfn from TI or Linear...there are some great. But dfn is not easy for everyone ! So I found, a not yet released (new) ic, and I am waiting samples from a local distributor.
It's XC9265:
- lot of variant
- 2 to 6V vin
- the 2.9V Vout samples I am waiting for is rated 0.7uA in active mode.
- 90% efficiecny at 10-15uA light load
- and not the least, SOT25 package.
Wow, another crazy nugget! Hum..I think manufacturers should reward me, am I good at advertising ??? ahaha :laughing: And for the fun, preview of the buck rev with 0805 passives.
does it look better now @tbowmo ? your feedbacks are always appreciated :)And free of charge :laughing: Sorry...it just makes me laugh :)
Here an eval board I have designed for this buck.
As you can see on it, there still are :- 2x ferrite on Vout and Gnd
- as this buck is only one Vout. I added one mosfet to have a second enable/disable Vout2 . So we have Vmain always active(0.8u Iq), and a switchable Vsub.
Size of this eval board : 12x16mm
-
@tbowmo: thx. So I am happy.
I will post schematic soon, need to clean my notes! it's rather simple.@shabba: thx. I am thinking about it...I don't know for the moment the easier/cheaper way for me and you. China or homemade batch..and there is a fablab near my home, which is able to handle mini batch...
And it is chinese new year so I can't get a quote. I need to do the BOM now to evaluate. But I have tried to keep things cheap vs perf vs quality..It's 2layer (so cheaper, maybe for emi it would be better 4layer, but I will see), radio should not be included in price (we can choose which one so), atmel or passives are cheap, not too much ic. I am much more worried about sensors soldering china price...But I will see, it's planned. -
Really great project. Thanks for giving me ideas and inspiration. This was my next step to go for after my thermostat and dimmer project
-
For the box
Is the battery kept away from the antenna part of the design. My question is is the board longer than an AA battery including battery "connectors" -
If you have space issues i think you should go for 0402 size, its not that hard to solder if you have a magnifing lamp, a good soldering iron, a tweezers and some thin soldering iron :)
-
Yep I have already all these tools ;)
I have already soldered 0402, for sensebender for instance :) I ordered 3 boards at oshpark, couldn't wait! It works well.
But when I can, I prefer 0805, or 0603 min. My way to share. 0402, not everyone will try, nor 805 I know..! And I prefer to minimize mistake source , less small things, less error possibilities at prototyping. I could have choosed atmel vqfn too!
I like when I see someone sharing 0603/0805 files. When I see something 0402 and really need it, I make it 0805/0603 ;)
For this board I think 0603 min is ok. For the moment it's 0805, I will try to add a little bit more clearance before ordering it.
It could be a little bit smaller with 0402, but not much, there are antenna area, and battery connector, components on top... And between a 6 or 6.5cm pcb...hum is it really useful, I am far away of coincell size so! And I don't want to put radio on bottom, between the pcb and battery holder. it would add more thickness.Sensebender is a very special case, a challenge. It is the ultra mini sensor board. but no batt holder. Add it and a box, it's not the same size. There are minimal
