I did some measurements on this chip but I cannot get the power usage under 0.5mA in sleep mode.
When I remove the ground wire of the RFM95 the power usage in my setup drops to a few µA so I'm sure it is the RFM95 using power.
This should be much less, about 0.2µA according to the official PDF specs!
I'm using the Arduino-LMIC library and from what I see it really enters sleep mode. All other modes have a power consumption of at least 1.5mA.
Has anyone measured better power usage from this chip?