nRF700x: TCXO hardware configuration

[JordanYates]

The Commissioning and Characterization note for the nRF700x series (https://infocenter.nordicsemi.com/pdf/nan_043.pdf) says in section 2.1.2

An external temperature-controlled crystal oscillator can be used to avoid trimming. These devices are
typically more expensive, but this method avoids the need for executing the trimming algorithm on the
production line.

However I have been unable to find any information about how a TCXO should be connected to the modem.

The datasheet only mentions XOP and XON as analog inputs for a 40MHz crystal, and does not mention TCXO's at all.

The question is which pin should be connected to the TCXO output, and which pin should be connected to the TCXO power.

[Kenneth]

Hello,

Let me look into this. I don't think there is any pin to control the TXCO power, so I suspect that the TXCO must be running pretty much continuously as long the nRF700x is not shut down. Will this work for you in terms of power consumption?

Kenneth

[JordanYates]

It depends on the application. If it could be tied to the BUCKEN pin or similar that could work when the interface is only powered on periodically.

It wouldn't work at all if you are trying to use TWT or other power saving methods.

[Kenneth]

Hi,

I can't find any way to control that TXCO power, so I guess that must be handled by the host MCU, and this likely will badly affect the current consumption.

Description how to connect and use a TCXO:

Connect TCXO output to Pin 17 (XOP) with a coupling capacitor (series)

- Typical cap value 10nF

- Typical output amplitude 0.4Vp, clipped sine wave. Max 1V amplitude.

Pin 18 (XON) must be floating N/C

Best regards,
Kenneth

[needhelp]

I just want to confirm that 10nF is not a typo. My experience with using TCXO with a coupling capacitor has usually been 10pF to 100pF range.