Yes you did the right thing. I am a drop it in the drawer person. Hate when those batteries make a bang.
On Tue, Dec 15, 2020 at 5:06 PM Matthias Welwarsky <[email protected]> wrote: > On Dienstag, 15. Dezember 2020 19:22:14 CET paul swed wrote: > > Hello to the group Nigel is correct the way the schematic is drawn the > > Regulator will feed the battery and most likely cause it to burst. > > It should be 1 diode in series with the regulator and 1 in series with > the > > battery so that the regulator can not charge the battery. > > Yes, that's what I discussed with Nigel off-list. The two diodes in series > create a voltage difference of 1.4V, so as long the battery voltage is > above > 1.9V, no current will flow through the diodes at all and the battery is > safe. > > However, there is a greater-than-zero probability that a board will just > be > dropped into a drawer with the battery in place, fully draining it > eventually. > If it's then powered up again, chances are that a substantial current will > flow into the battery and potentially cause a fire, explosion, etc. > > I've therefore updated the design and put a small Schottky diode in series > with the battery. I selected a part with small leakage current ( 0.5µA > typical). But of course a regular silicon diode like 1N4148WS will work as > well, at the expense of wasting some of the energy of the coin cell. > > > Nice design you have created. > > Thanks - Hopefully it will also work :-) > > > Regards > > Paul > > WB8TSL > > > > On Tue, Dec 15, 2020 at 11:55 AM Nigel gm8pzr via time-nuts < > > > > [email protected]> wrote: > > > Hi Mathias, > > > I'm assuming you're using a coin cell for back up, so wondering if one > of > > > the diodes shouldn't be in series with the battery, with both cathodes > to > > > V_BCKP? > > > Nigel GM8PZR > > > > > > > > > I've updated the repository on github with the latest design files. The > > > breakout board is now final as far as I'm concerned. > > > > > > I managed to implement all the requested features, this includes the > > > backup > > > battery and also the buffered PPS output with SMA footprint. > > > > > > Next step on my side will be to order a small batch of PCBs. There's > not > > > much > > > on them and I guess I will end up with around 25? for 5 boards fully > > > assembled, shipping not included. > > > > > > I eventually removed the I2C pull-ups again, thanks to Patrick Tudor > for > > > the > > > hint. The footprints are still there, I only removed them from the BOM. > > > > > > Schematic and a screenshot of the top and bottom sides attached. > > > > > > BR, > > > Matthias > > > _______________________________________________ > > > time-nuts mailing list -- [email protected] > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and > follow > > the instructions there. > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
