https://devzone.nordicsemi.com/f/nordic-q-a/27560/usb-supply-without-vdd-supply-in-nrf52840what happens when USB supply is powered but VDD isn&#39;t powered? The internal USB LDO is working ? DECUSB go to high or not ? Is there a leakage current from usb to nRF? Thanks,en-USTelligent Community 13Thu, 30 Nov 2017 15:29:42 GMThttps://devzone.nordicsemi.com/thread/108800?ContentTypeID=1Thu, 30 Nov 2017 15:29:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:3f59ca80-006f-42a0-9982-99eb7c1b3eb7Sigurd<p>Hi,</p> <p>Please see the <a href="https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52840.ps/power.html?cp=2_0_0_15#concept">nRF52840 POWER section at infocenter</a>.</p> <p>High voltage mode is entered when the supply voltage is only connected to the VDDH pin and the VDD pin is not connected to any voltage supply. <em>(USB (VDDH = VBUS), VBUS must be connected to VDDH if USB is to be used)</em></p> <p>The voltage regulators can be configured in several ways, depending on the selected supply voltage mode (normal/high) and the regulator type option (LDO or DC/DC).</p> <p>By default, the LDO regulators are enabled and the DC/DC regulators are disabled. Registers DCDCEN0 and DCDCEN are used to independently enable the DC/DC regulators for the two stages (REG0 and REG1 respectively). DECUSB is Decoupling for USB regulator output 3.3 V</p><div style="clear:both;"></div>