On a different thread (
https://lowpowerlab.com/forum/low-power-techniques/stuck-in-listen-mode-listen-mode-bug-with-workaround/msg16974/#msg16974) I offered to design a simple breakout board for the AB18x5 RTC, so that anyone who wants to try it out will have a way to do so. For those who don't already know, that AB18x5 RTC uses very little power, making it a good choice for battery based projects.
Attached is the first pass on the breakout board, which should fit easily into any 2.54mm pitch breadboard. A few open issues:
1. I wasn't sure if connecting the oscillator directly to pins 15 and 16 might somehow (?) impair its performance. Also, it's not really necessary. So, I left them disconnected, but I added some jumper pads so you can connect them after-the-fact if you want to.
2. I didn't include a GND copper pour. Not sure if in this case it would help or cause problems, so I left it out. However, if someone thinks it should have one, I could add it.
3. The AB18x5 comes in two different versions: one uses I2C, and the other uses SPI. Rather than do two different boards (with two different silk screens to label the pins), I just numbered the pins. That way you can use the same board for either chip.
I'll wait a bit for comments. Then I'll finalize the design and ship off the files to a fab. After I receive the board and verify that it works, I'll then post the gerber files.