nRF52811 Clock Source

RE: nRF52811 Clock Source

Håkon Alseth — Wed, 23 Oct 2024 08:20:19 GMT

Hi,

That is reference designs with DCDC converter enabled, and with traditional LDO regulator setup. Ie. the difference is in how you power the device.

Kind regards,

Håkon

RE: nRF52811 Clock Source

Kaveh.M — Tue, 22 Oct 2024 13:57:06 GMT

Thanks that was helpful. In the last link you shared, what is the difference between "Figure 6. CAAA WLCSP with DC/DC regulator setup" and "Figure 5. CAAA WLCSP with internal LDO regulator setup"?

RE: nRF52811 Clock Source

Håkon Alseth — Tue, 22 Oct 2024 13:47:58 GMT

External 32k is optional, as shown here:

https://docs.nordicsemi.com/bundle/ps_nrf52811/page/ref_circuitry.html

Current consumption for both scenarios (ie. using internal 32k RC oscillator and external 32k quartz) is listed in the former link.

RE: nRF52811 Clock Source

Kaveh.M — Tue, 22 Oct 2024 13:40:34 GMT

Thanks. Can I skip using LFXO and just use HFXO for all functions?

How the power consumption looks like in this case?

RE: nRF52811 Clock Source

Håkon Alseth — Tue, 22 Oct 2024 13:34:11 GMT

[quote user="Kaveh.M"]Ok. What if I dont want to use any external crystal? Can I just use internal sources for clock? [/quote]

Not if you need to use the RADIO peripheral. the 32 MHz xtal is a requirement for that.

[quote user="Kaveh.M"]What would be difference in power consumption in deep sleep mode when using internal clock sources compared with using 2 external crystal for 32kHz and 32MHz? [/quote]

You normally do not want the HFCLK to run during sleep, but the LFCLK would normally run. Here's the current consumption scenarios for running LFCLK (LFXO + internal LFRC):

https://docs.nordicsemi.com/bundle/ps_nrf52811/page/_tmp/photon/autodita/CURRENT/parameters.id_current_sleep.html

Kind regards,

Håkon

RE: nRF52811 Clock Source

Kaveh.M — Tue, 22 Oct 2024 13:30:22 GMT

Ok. What if I dont want to use any external crystal? Can I just use internal sources for clock?

What would be difference in power consumption in deep sleep mode when using internal clock sources compared with using 2 external crystal for 32kHz and 32MHz?

RE: nRF52811 Clock Source

Håkon Alseth — Tue, 22 Oct 2024 06:38:54 GMT

[quote user="turboj"]The 32 MHz quarz is required for bluetooth (and other radio) operation. [/quote]

This is true.

[quote user="Kaveh.M"]well, I dont see anywhere in the datasheet that external 32MHz crystal is mandatory[/quote]

You need to use an external 32 MHz xtal when using the RADIO peripheral.

HFXO requirements are listed here:

https://docs.nordicsemi.com/bundle/ps_nrf52811/page/clock.html#ariaid-title33

Kind regards,

Håkon

RE: nRF52811 Clock Source

Kaveh.M — Mon, 21 Oct 2024 14:12:46 GMT

well, I dont see anywhere in the datasheet that external 32MHz crystal is mandatory to be used along with 32.768kHz crystal, if we are using an external clock source.

I have used nRF82832 and nRF52833 in the past only using an external 32.768kHz crystal without any problem. The radio worked on those using only the low frequency external clock.

RE: nRF52811 Clock Source

Turbo J — Sat, 19 Oct 2024 07:42:35 GMT

The 32 MHz quarz is required for bluetooth (and other radio) operation. I would also recommend it when using UART.