I have designed a second version of the Ameba Stamp and have renamed it to "BW16 Stamp" which is more intuitive to most makers.
In the previous log, I have mentioned that I would like to replace the LDO MAS1117 with DCDC convertor to save power from the relatively high quiescent current (2mA) that AMS1117 draws, but after searching for the parts and availablity, it appears that the global chip shortage still persists 😅
Plus, replacing with DCDC convertor will also introduce many more passive components as compared to LDO, this will result in bigger PCB layout, higher price point and more complex PCB design.
Therefore, I have done some research and located a new LDO -- RT9013, it works similar to AMS1117 LDO, but it requires much less passive components (only 2 de-coupling capacitors) and much much less quiescent current (≈25uA), which is about 80 times less than AMS1117 LDO. The footprint of this IC is also much smaller than both the DCDC convertor and AMS1117, the price and availability is also a big bonus,
The only downside however, is that it is only able to deliver 500mA power at max (AMS1117 delivers 1A), but in the 1 Ohm Resistor Energy Meter project, we have measure and observed that the max instantaneous current drawn from BW16 is around 200mA, so 500mA is good enough for many low power profile projects.
The schematic is completed
This is how it looks in 3D rendering,
The second version will be open sourced later, so stay tuned for more updates~