when nrf52840 open dcdc and usb ,it will reboot.

RE: when nrf52840 open dcdc and usb ,it will reboot.

Andreas — Thu, 26 Sep 2019 12:49:18 GMT

Hi,

Revision C should not be used due to errata 197 and 202. You should contact your sales manager to get some samples of revision D and test this.

Best regards,

Andreas

RE: when nrf52840 open dcdc and usb ,it will reboot.

Terrel — Thu, 26 Sep 2019 01:20:25 GMT

1.The mcu marking is QIAAC0.

2.VDD_nRF is only for nRF52840,it donot connect anything.

3.If REGOUT is higher than 1.8v, the system will still work.Because nrf52840 is now set to 2.1VLDO mode, the system is running normally.

4.If turn off the USB code and then plug/unplug USB, nrf52840 is not reset

RE: when nrf52840 open dcdc and usb ,it will reboot.

Andreas — Wed, 25 Sep 2019 13:59:21 GMT

Hi,

What revision chip is on the boards, C or D (is the marking on top QIAAC0 or QIAAD0)?

Is there anything else being supplied on VDD_nRF? Is there any change in behaviour if the REGOUT is higher than 1.8 V? Can you share a scope plot of what the VDDH line and VDD line look like when you plug/unplug the USB cable, is there any difference between failing and non-failing boards?

Best regards,

Andreas