Feedback on XIAO nRF54L15 Power Design
I’ve been doing extensive low-power testing on the XIAO nRF54L15, and overall it’s a very impressive board—especially now that the nRF54L15 has Arduino support. It has the potential to be one of the best ultra-low-power platforms available.
However, I’ve run into a significant limitation related to the onboard voltage regulator.
The board uses the TPS62843, which is a high-quality step-down (buck) converter and works very well when VBAT is higher than 3.3V (e.g., LiPo scenarios). In that region, efficiency is excellent and current consumption is very low.
The issue appears when VBAT is around 3.3V—exactly the range used by coin-cell batteries. At this point, the regulator enters a near-dropout region, and current consumption increases significantly. Below 3.3V it improves slightly, but remains higher than expected for ultra-low-power applications.
This behaviour makes the current design difficult to use with coin cells or other low-voltage sources, where minimising quiescent current is critical.
Suggestions for Future Revisions
To make this already excellent board more flexible and suitable for ultra-low-power designs, I’d suggest:
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Use an ultra-low quiescent current LDO instead of (or alongside) the buck
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The antenna switch design is good, but adding solder jumpers or easier power gating would allow users to fully disable it when not needed
Buck converters are excellent for many scenarios, especially with higher input voltages. However, for ultra-low-power, low-voltage applications (like coin cells), they are not always the best choice—particularly near dropout.
Thanks for the great work so far—this board is very close to being ideal for ultra-low-power development.