All - We have an nRF52340 based design which when tested with the system off demo available in NCS v1.5.1 gives a system off current of <1uA.
We have a second design using the same hardware base which also incorporates an nRF21540 FEM. In this case, the system off current is approximately 500uA.
Various combinations of FEM control lines have been checked (output driving PDN low, input with pull down pulling PDN low), all lines being pulled up or down as described in the nRF21540 datasheet. None have had any effect.
One area we're unsure relates to the FEM MODE pin. Does this need an external pull-up/down depending upon the desired configuration, or can it be directly coupled to VDD/VSS depending upon desired configuration?
Is there a complete reference design available for us to review?
Many thanks,
Greg.
