nRF52840 power configuration

RE: nRF52840 power configuration

Jared — Mon, 24 Sep 2018 12:53:41 GMT

Hi Chris

We had some problems on devzone earlier today but it's fixed now. Please create a new ticket for your question.

Cheers

Jared

RE: nRF52840 power configuration

Jared — Mon, 24 Sep 2018 12:52:09 GMT

I'm not sure I understand your setup correctly. You mention that your source is 1.8 V, why is your battery range 4.2 V to 3.3 V than?

As stated in the product specification: "In normal voltage mode, only the REG1 regulator stage is used and the REG0 stage is automatically disabled. In high voltage mode, both regulator stages (REG0 and REG1) are used."

The high-voltage mode does therefore use more energy as the system use a two-stage regulator setup.

Jared

RE: nRF52840 power configuration

vivekt — Mon, 24 Sep 2018 09:04:02 GMT

Also then what will be the IO voltage range(VOH/VIH) for all the GPIO pins.

RE: nRF52840 power configuration

vivekt — Mon, 24 Sep 2018 09:01:42 GMT

4.2V to 3.3V

RE: nRF52840 power configuration

Jared — Mon, 24 Sep 2018 09:01:04 GMT

What is the voltage range of your battery source?

Cheers

Jared

RE: nRF52840 power configuration

Chris — Mon, 24 Sep 2018 08:06:07 GMT

sorry for capturing that ticket (I can't create a new one since all dropdowns are empty).

But I think it's alright to post here as it has somewhat to do with VDDH:
We want to keep our design flexible, so basically I could be powered by VDD or VDDH. If I run our PCB with 3.3V at VDD, SWD works fine.
If I connect 5V to VDDH, I can see 1.8V at VDD but SWD (connected to DK) does not work. Is there a register to write to make it work or so?

Circuitry is Configuration No.4

edit: could it be that SWDIO has to have the exact same voltage level? While testing something different I was powering the PCB with 3.5V and SWD from DK (GND connected) is not working. Just switching what has been 3.5V to 3.3V supply from DK and everything is working perfectly again

RE: nRF52840 power configuration

vivekt — Mon, 24 Sep 2018 07:54:57 GMT

Then I will not be able to use Config 3. Then should I go to Config 2 mode . Connect Battery/Sys voltage around 3.7V to the VDDH pin. VDD will not be connected to the source 1.8V. Will the High voltage mode consume more power than the normal mode.

Regards

Vivek.T.

RE: nRF52840 power configuration

Jared — Mon, 24 Sep 2018 07:44:35 GMT

No, the minimum value for VDDH should be 2.5 V. The operating condition for VDD and VDDH is specified in chapter 5.3.8.1 in the product specification.

Jared

RE: nRF52840 power configuration

vivekt — Mon, 24 Sep 2018 07:03:43 GMT

In the datasheet section 8 it is mentioned that VDDH typical value should be between 2.5V to 3.5V. Is this for high Voltage mode only. When using config 3 in normal voltage mode the VDDH can be 1.8V. Is my understanding correct.

RE: nRF52840 power configuration

Jared — Fri, 21 Sep 2018 13:50:05 GMT

The configuration that you should use depends entirely on the voltage range of your battery when it's in the depleted and full state. The entire battery range should be within either VDDH's operating range or VDD's. So if you battery is minimum 1.7 V when its depleted and maximum 3.6 when its full, you should use VDD. Which means that you should use configuration 3 normal mode. You should also make sure that the USB charging voltage is within the operating range of the VDD. This can be achieved by using a regulator between the charging voltage and VDD.
You can download the reference design here.

Cheers

Jared