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Excess Current Consumption Running B-L072Z-LRWAN1 From Battery??

Question asked by Andrew Neil on Dec 11, 2017
Latest reply on Apr 10, 2018 by Andrew Neil

I have removed all the solder bridges & links to minimise stray consumption.


When I measure the combined current through JP3 and JP1 (ie, MCU & RF), it is ~0.87mA between Tx pulses.


(SB19,14,17 are removed; JP2 is not fitted - so no current to USB_LRA)


But, when I power the board from the battery, and measure the battery current, I see 1.95mA

(SB18 is removed)


The ST LD39050 regulator (U7) is supposed to be "low quiescent current": the datasheet says it should only, typically, be taking 100uA at 500mA load - so we should be nowhere near that!


So where is this extra milliamp going??



To clarify: the ~0.87mA to MCU & RF is measured while powered from the battery.