Hardware configuration with no USB and no bluetooth

[Luigi Antuono]

Hello,

I am writing this thread to ask what would be the hardware configuration for the QKAA version of the nRF5340 chip if I don't want to use the wireless features of the chip (both NFC and Bluetooth).

I found that the configuration no. 3 you propose in the datasheet is quite close to what I am looking for, but still the Bluetooth is considered to be used.

So my question is: 

"How the circuit configuration will change if I don't need Bluetooth and the power will be taken from the battery?"

Here I link an image where I mark what I am expecting to remove.

Would you please help me understand what the components are that I can remove without affecting the chip's performance?

Thanks for your time.

Regards,

Luigi Antuono 

[ketiljo]

Hi Luigi

You can see how the regulators are internally connected here: 

https://docs.nordicsemi.com/bundle/ps_nrf5340/page/regulators.html

DECR and DECD each supplies the network and application CPU cores. 

The ANT pin can be left floating when the radio is not used. Noot much else you can remove I'm afraid. Except the inductors if you don't need DCDC mode.

Best regards,

Ketil Aas-Johansen

[Luigi Antuono]

Hi ketiljo,

Thanks for the link you mentioned, but still, I am not sure if my question was clear enough.

Based on this block diagram:

If I won't use the radio features of the chip (so that VREGRADIO:DCDCEN will be low), can I left DCCD and DECD pins floating?

Are they used also to power other stuff other than the radio-related sections of the chip?

Thanks for your time.

Regards,

Luigi

[ketiljo]

The nRF5340 has two CPU cores. The application core is supplied via DECD  and the network core is supplied via DECR. The radio is powered together with the network core. The main core is the application core so you will need this. 

Now, the regulators have several modes. Then can operate in LDO mode and DCDC mode, where the latter requires the inductors to be in place. Since you're not using the radio, you can remove the inductor for the DECR DCDC (LDCC),  but the regulator will need the capacitor to operate properly. For the lowest current draw, it's recommended to keep the DECD inductor (LDCCD).

[Luigi Antuono]

I just realized I was confusing about what I said. Sorry for that.

What I meant is, because I will not use the radio features of the chip, can I have the DECR and DCC pins floating? 

I am sorry that during the whole conversation (and also in the image I attached at the beginning) I was instead referring to DCCD and DECD, that was wrong of me.