The average current drawn by the nRF21540 FEM can be measured using an ampere meter. This method monitors the current in series with the nRF device. A true Root Mean Square (RMS) ampere meter is recommended.
To measure the average current drawn by the nRF21540 FEM perform the following steps.
- Prepare the Evaluation Kit (EK) as described in Set up the evaluation kit.
- Connect an ampere meter between pins 1 and 2 of connector P5 as shown in the following figure.
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Do one of the following:
- Ensure that the FEM is in a state where it draws a constant current.
- Ensure that the activity on the device changing load current, such as Bluetooth LE connection events, is repeated continuously and has a short cycle time of less than 100 ms so that the ampere meter averages complete load cycles and not parts of the cycle.
- Set the average timing of the ampere meter to a long interval, such as 1 s or longer.
- Set the dynamic range of the ampere meter between 1 µA and 150 mA, so that it is wide enough to provide accurate measurements.
Figure 1. Current measurement with an ampere meter
