nrf52833 Power Reset

RE: nrf52833 Power Reset

Einar Thorsrud — Mon, 05 Jul 2021 10:59:25 GMT

Hi Lyrics,

[quote user="lyrics"]So, according to the designed circuitry, 32.768khz must continue to oscillate even if the current 5V power is turned off.[/quote]

There is no backup voltage concept in the nRF devices, so this depends on how you have implemented your design. Can you share schematics and explain your HW design regarding this? I assume you are using the high voltage mode VVDH as you have such an high supply voltage? In high voltage mode, the minimum supply voltage (VVDH) is 2.5 V.

[quote user="lyrics"]So, according to the designed circuitry, 32.768khz must continue to oscillate even if the current 5V power is turned off.[/quote]

I see. I cannot say anything without knowing more about your HW design, though.

[quote user="lyrics"]the main power is turned off and no longer oscillates (back-up voltage is still present).[/quote]

Is this the 32.768 kHz crystal oscillator of the nRF? If so you need to put the nRF in low power mode yourself (system on, all peripherals expect LFCLK and RTC turned off). If it is a fully external clock then I cannot say what you need to do, other then somehow cut supply voltage to the nRF.

[quote user="lyrics"]

Is what I understand correct? Or what is the reason for the problem situation that I mentioned above?

I hope my question was delivered well.

[/quote]

I think I understand the question, but as mentioned you need to explain details about your WH and share schematics.

Einar

RE: nrf52833 Power Reset

lyrics — Mon, 05 Jul 2021 01:44:18 GMT

Hi,

My manufacturing board has a small back-up voltage, so it can be operated at low power even after the 5V power is turned off. I want to use that low power to operate the program in idle mode through the 32.768khz external oscillator even when the main board is powered off.

So, according to the designed circuitry, 32.768khz must continue to oscillate even if the current 5V power is turned off. However, at present, the main power is turned off and no longer oscillates (back-up voltage is still present).

I searched for reasons for this, look at this post and this post.
So I thought it wouldn't work because it would reset the mcu internally if it fell below a certain current. (back-up voltage is in range 1.8V- 5.5V)

Is what I understand correct? Or what is the reason for the problem situation that I mentioned above?

I hope my question was delivered well.

BR, lyrics

RE: nrf52833 Power Reset

Einar Thorsrud — Fri, 02 Jul 2021 11:28:44 GMT

Hi,

I am not able to fully understand the situation. Can you try to elaborate?