WisBase RAK5005 vs RAK19007 - ON-state quiescent current for 3v3_S

I noticed the RAK19007 replaced the TPS27082L P-FET switch for 3v3_S with a P-FET driven by a bipolar inverter. As a result, the ON-state quiescent current went from ~1.2uA to ~1.1mA, problematic in an application where the 3v3_S rail is used for external-interrupt pull-ups (a completely reasonable thing to do) with the MCU in sleep.

From what I can tell, only the P-FET is required, since the MCU core drives IO2 with a 3v3 signal. A 2M pull-up is more than sufficient to keep 3v3_S off during MCU reset. This does mean IO2 would invert where IO2 = 0 turns on 3v3_S, though. ON-state quiescent current would be under 2uA.

Alternatively, substantially increasing R20 from 4k7 to, say, 2M, and replacing Q8 with, say, a DTC with 100k base resistor, could get quiescent ON-state current under 40uA. Substantially better but not as good as the TPS27082L.

Requests for a future rev perhaps.


Update: swapping the same Core and IO to a 5005 vs 19007, I see 1.08mA sleep current on the 19007 and 20.8uA sleep current on the 5005. About 15.8uA of that is the STM32WLE5 MCU Core + and 1.7uA is the battery voltage divider.

Hi Dana,

we are aware of this and it is planned to change it with the next HW revision of all WisBlock Base Boards.

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Awesome - thank you, this is welcome news. Any notion of the time-frame the updated Base board will be available?

Depends on stock we have in the warehouse. I have no information about that, but I reminded our R&D team to change the BaseBoards to a better solution for switching 3V3_S. So that on the next batch order it will be changed.

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Thank you - looking forward to the updated Base board.