My nRF52840 Module keeps resetting after I changing the mode to LDO

[Harvey.Zhang]

Hi.

I made the smallest system module using nRF52840. The schematic diagram is as follows.

My reference design for power supply is as follows,

For Firmware.

I copied the routine nRF Desktop in nRF Connect SDK V3.0.2 for test and added the following code to switch internal power supply to LDO in app.overlay.

At the same time I added the following code for test in the same file.

My module looks like keeps resetting after I burn the firmware, according to the waveform of P0.12.

May I ask how I can make the routine run normally on my module?

[Priyanka]

Hi,

I could see the following issues in your schematic:

1. This capacitor is not required here:

2. The components and values in your ANT section is very different from our reference, which is:

We recommend following it exactly for guaranteed performance.

3. This is N.C in the reference:

4. Are you using the USB? If yes, you need to connect 4.7uF to ground from the VBUS pin and if not using, then you need to directly ground the VBUS pin.

5. Please make sure you have chosen the crystal caps accordng to the crystal frequencies:

Regards,

Priyanka