High current draw (~370uA) from external HF Oscillator

[ItsAmelia]

This is a follow-on from this question, but I will include all relevant information here.

I have a custom board using an NRF52810 (Specifically, N52810-QFAAD1-2145FM). It is based on the reference circuit with DC/DC regulator and both external crystals, with basically the entire reference circuit copied exactly into my design. My entire design is available here as a KiCAD project, with images of the HF Oscillator part of the PCB attached below. The exact crystal I am using is HD-7D032000F01.

With the external 32MHz crystal oscillator disabled, it draws ~1uA in sleep mode, as I would expect. With the external HF oscillator enabled, it draws ~370uA. I assume there must be a problem with my PCB design, but I do not know how to go about debugging this. Are there any general tips you could offer for identifying the issue?

I did run a VCC line on the back of the PCB directly under the crystal. Could that cause issues? (Edit: This line is not critical, so I tried cutting it and connecting it to ground instead. This had no impact on the current draw)

[Kenneth]

Hello,

I have not looked at your layout, but based on the numbers I am not sure if there is anything wrong here? 

I can find that the online power profiler show that the average current during standby (exteral HFCLK started before radio is used) show 0.4mA, ref:

 Online Power Profiler for Bluetooth LE  

Kenneth

[ItsAmelia]

What is the difference between Standby in the power profiler, and System ON mode with all peripherals idle? I am in the latter scenario, so all of my peripherals (including the RADIO) are entirely disabled. Should I also be disabling the HFXO in this case?

According to the current consumption page of the documentation, in sleep mode, with all peripherals idle, current consumption should be ~1-2uA (depending on RAM retention, etc.). Did I misunderstand this, and it only applies with the HFXO disabled?

[Kenneth]

Hi,

Typically the HFXO is only needed when you are using the radio, in which case there is a radio protocol running (e.g. Bluetooth), the radio protocol will automaticaly start and stop the HFXO when it need a high accuracy clock. There is no need for the application to start the HFXO.

Kenneth