https://devzone.nordicsemi.com/f/nordic-q-a/34786/source-of-1-0-khz-current-spikeOn my nRF52 DK, I&#39;m seeing *something* pull down VCC by about 50 mV once every millisecond (1KHz), and I&#39;m trying to identify its source. (This is only important because using VCC to drive some sensors. Yes, I suppose I should create my own voltage sourceen-USTelligent Community 13Sun, 27 May 2018 23:33:42 GMThttps://devzone.nordicsemi.com/thread/133546?ContentTypeID=1Sun, 27 May 2018 23:33:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ed9c90ea-1099-4c8f-a23c-839e1cd5f18cAustin<p>You indicated that you&#39;re transmitting via USB.&nbsp; A USB&nbsp;<a href="http://www.usbmadesimple.co.uk/ums_7.htm">Start Of Frame (SOF)</a>&nbsp;packet is sent by the USB host every 1ms for full speed USB links.&nbsp; If the MCU is configured to interrupt on SOF events, this may explain additional current draw at 1KHz.&nbsp; These events would be asynchronous to your application.</p> <p>You could try unplugging USB to see if this is the source of the problem.&nbsp; If you&#39;re powering the target via USB, try a &#39;power only&#39; USB cable without D+/D- connected.</p><div style="clear:both;"></div>