Power consumption

nRF9160 has two power inputs: VDD for internal parts and VDD_GPIO for GPIO pins. VDD_GPIO consumption should be observed in measurements, because load on any GPIO pin is visible on VDD_GPIO.

nRF9160 contains an internal DC/DC converter operating in a hysteretic mode when the device is in a low power consumption state. In this mode, the internal DC/DC periodically charges supply capacitors. The charging cycle creates spikes in current consumption. During a charging period, current consumption is typically in the mA range, but during a quiet period it can be less than 1 µA.

The performance of the test equipment should be carefully considered when setting up a power consumption measurement system. The most important criteria are good sensitivity for low currents, high dynamic range, and good sample rate. For example, Keysight 6715C power analyzer with auto-ranging power modules and Keithley DMM7510 multimeter are viable options.

PSM, cDRX, and iDRX current consumption example shows an example of nRF9160 waking up from the Power Saving Mode (PSM) mode, performing a Tracking Area Update (TAU) towards the LTE network, entering connected mode Discontinuous Reception (DRX) for three seconds, and finally entering idle mode DRX. The RF transmission is done with maximum power. The resulting peak current consumption is approximately 300 mA.

Power consumption between the idle mode DRX paging periods is in the µA range. In PSM, cDRX, and iDRX current consumption example, the zoomed-in image from that period shows typical PSM mode consumption with a DC/DC converter charging pulses.

Figure 1. PSM, cDRX, and iDRX current consumption example
PSM, cDRX, and iDRX current consumption example
Note: Power consumption is heavily impacted by network conditions, and the settings and may vary significantly.

For more information on measuring current consumption on the nRF9160 Development Kit (DK), see Measuring current in nRF9160 DK User Guide.