The current drawn by the nRF52840 System on Chip (SoC) can be monitored on the nRF21540 DK.
Current can be measured using any of the following test instruments:
- Power Profiler Kit II (PPK2)
- Oscilloscope
- Ampere meter
- Power analyzer
Power analyzer and Power Profiler Kit measurements are not described in this document. For more information on PPK2, see Power Profiler Kit II.
For measurement instructions, see Measure current profile with an oscilloscope and Measure average current with an ampere meter.
The nRF52840 SoC has two possible power supplies: VDD (1.7 V to 3.6 V) and VDDH (2.5 V to 5.5 V). The nRF21540 DK is prepared for measuring current on both domains. This section describes how current is measured on the VDD domain, but the process is the same for the VDDH supply. See the following table for the corresponding components.
| Component | VDD | VDDH |
|---|---|---|
| Measurement connector | P22 | P23 |
| Solder bridge | SB40 | SB41 |
| Series resistor | R90 | R91 |
- It is not recommended to use a Universal Serial Bus (USB) connector to power the Development Kit (DK) during current measurements. However, when measuring current on an application using the USB interface of the nRF52840 SoC, USB must be connected. It is recommended to power the DK from the external power supply on connector P21 (1.7 V to 3.6 V), or through the Li-Poly connector J6 or P27 (2.5 V to 5.0 V).
- The current measurements are unreliable when a serial terminal is connected to the virtual serial port.
- After programming the nRF52840 SoC, the USB for the interface MCU must be disconnected.
For more information on current measurement, see the Current measurement guide tutorial.