Current spikes when DCDC is on

[Oliviertl]

Hi,

I use the nrf52 dk(PCA10040). When monitoring the current consumption of the advertising with the DCDC enabled, we see some current spikes. Why?

Here is two screenshot, one with the dcdc enabled and the other with the dcdc disabled:

[Stian Røed Hafskjold]

This is the regulator operating in refresh mode. From the spec:

• Auto-controlled refresh modes for LDO and DC/DC regulators to maximize efficiency

Both the LDO and DCDC have two modes of operation. Normal mode and refresh mode. Refresh mode is used when the current consumption is low in order to further maximize the efficiency. Refresh mode works by charging up internal caps regularly to provide power to the chip. So the spikes you see is the inrush current to the caps.

Whether or not the regulator should be in normal mode or refresh mode is automatically controlled by the chip itself. So from your plots you can see that the chip decided that refresh mode is the most efficient when DCDC is enabled, and normal mode with LDO.