Hardware design nRF52840

[Sreejith Sundh]

Hi,

I am developing a BLE sensor based on nRF52840 SoC (QIAA aQFN 73).  I would like to get some clarrification regarding following points while hardware design. Thanks for your support and suggestions..

1. I would like to power the sensor circuit by nRF52840. If so Which configuration is better for my design. (I found the reference circuitry Configuration no. 4 is it the right configuration?)

2. If I am going with congiguration 4, I do not want want to use VBUS, because it is not planned to include USB in my design so is it fine to connect VBUS directly to ground ?

3. I would like to power VDD_HV using battery. What is the requirement for this VDD_HV (I mean the required minimum and maximum voltage and current for this supply). If I connect battery out output to VDD_HV, what is VDD_nRF? do I need to provide additional supply for VDD_nRF?

4. What would be the minimum and maximum voltage and current which I get from VEXT, when I go with circuit? How can I set the VEXT according to my requirement?

5. Is there any power supply circuit (battery and battery reverse current protection circuit) available in common for nRF52840?

I am completely a beginner in hardware design. I really thanking you for your support and time. Looking forward to hearing from you,

Thanks and Regards,

Sreejith

[JONATHAN LL]

Hello Sreejith, tanks for looking at our product for your project.


Looks like you did find some info in our Product specification(PS), most is stated there.

1. I would like to power the sensor circuit by nRF52840. If so Which configuration is better for my design. (I found the reference circuitry Configuration no. 4 is it the right configuration?)

If you where to share more info on how you want to use the SoC then it might be easier to comment on what would be the correct setup for you. Just want to clarify that the options that is shown in the PS is just a example of how it could be done. So it is possible to mix and match to some degree here. 

VEXT is for supplying external circuitry from the VDD. If this is what you think you need then config 4 and 2 is a fitting example. 
You can read more about the main supply and external circuitry supply here: https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_0_2#unique_1834109135 

We do help with HW layout and Schematic, and we do reviews of design, so feel free to ask for a review of you circuitry when you have put something together. 

2. If I am going with congiguration 4, I do not want want to use VBUS, because it is not planned to include USB in my design so is it fine to connect VBUS directly to ground ?

If you are going with Config 4, then yes you can edit the example config to your requirement. So with no USB it would look like this:

So VBUS to ground, and remove the DECUSB decupling capacitor. 

3. I would like to power VDD_HV using battery. What is the requirement for this VDD_HV (I mean the required minimum and maximum voltage and current for this supply). If I connect battery out output to VDD_HV, what is VDD_nRF? do I need to provide additional supply for VDD_nRF?

You can check out the PS section POWER to find the table with Electrical spesificaitons: https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_7#unique_706563143 

MAX 5.5V on VDDH
MIN 2.5V  on VDDH


If you are using High voltage mode then you only need to supply power to VDDH, then the internal regulator will provide output on VDD. Example is in the Regulator configurations, so lets look at figure 4.

this depicts the High voltage mode with DCDC. Here you can see that the "supply" is only on the VDDH pin. So on VDD you will have the output from REG0, the internal regulator. 

So no, you do not need to provide an extra supply on VDD, this is done interlay when in High voltage mode. 

4. What would be the minimum and maximum voltage and current which I get from VEXT, when I go with circuit? How can I set the VEXT according to my requirement?

You can find all the info on what can be supplied from VDD here: https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_7_1#unique_1706523351 


Checking the REGOUT0 we can se the options:

Default is 1.8V, max is 3.3V, but remember the maximum output voltage from this stage is given as VDDH - V_VDDH-VDD. 

5. Is there any power supply circuit (battery and battery reverse current protection circuit) available in common for nRF52840?

No. 



Feel free to ask for anything else if it is unclear. You can also search here in Devzone on topics of interest, might find that someone has asked the question before. 

We also have some guides for the nrf52, General PCB design guidelines for nRF52 series - Hardware design, test and measurement - nRF5 SDK guides - Nordic DevZone (nordicsemi.com)

Regards,
Jonathan

[Sreejith Sundh]

Thank you Jonathan for your response!!

JONATHAN LL said:

If you where to share more info on how you want to use the SoC then it might be easier to comment on what would be the correct setup for you. Just want to clarify that the options that is shown in the PS is just a example of how it could be done. So it is possible to mix and match to some degree here. 

Yes, I have seen the reference circuitry, but I found some difficulty in hardware design. I would explain my requirement in detail. I would like to make a peripheral ble acceleration sensor. SO the acceleration sensor which requires 3.3V power supply. I have two option one is power the sensor and nordic (nRF52840 SoC) seperately and second one is power the nRF52840 VDDH and power the sensor from nRF52840 VEXT. I do not have USB. So the reference circuitry configuration 2 and 4, I found as best solution. But I read about the use of DCDC regulator will be the best choice to optimize the power consumption. That is why I asked for Reference circuitry Config. 4. What would you suggest here?

Also If I am using config 4 (or 2), I am supplying power only to the VDDH, I can take out VDD (1.8 to 3.3 V) from any of the VDD pin, but what I have to do with those remaining VDD_nRF pins and their corresponding capacitors? (I mean what will do with the pins (B1, A22,  AD14) while layout design?

JONATHAN LL said:

So VBUS to ground, and remove the DECUSB decupling capacitor

This is clear now!! Thank you..

JONATHAN LL said:

Default is 1.8V, max is 3.3V, but remember the maximum output voltage from this stage is given as VDDH - V_VDDH-VDD.

What is denoted by V_VDDH ?, Lets assume I have to get VDD or VEXT of 3.3V (The highest psooible value) from nRF52840 what would be the VDDH value? how can I configure REG0 to get output or VDD of 3.3V? Is there any example (code) to configure REG0 (I am using nRF52840 SoC with S140 and nRF5)?  

JONATHAN LL said:

Is there any power supply circuit (battery and battery reverse current protection circuit) available in common for nRF52840?

Here I asked about battery power supply circuit for the SoC, I refered to nRF52840 DK schematic, and found that they uses switches along with reverse protection circuit. So is there any recommended battery protection or regulator circuit while designing with nRF52840 SoC?

Once again many thanks for your valuable comments and support.

Thanks and looking forward to hearing from you,

with Regards,

Sreejith

[JONATHAN LL]

Sreejith Sundh said:

But I read about the use of DCDC regulator will be the best choice to optimize the power consumption.

Yes, DCDC is something we recommend if power consumption is a concern. So Config 4 would be the go to. But it requires extra components so if price is of concern then DCDC can be removed to spare some cost on the extra components. 

Sreejith Sundh said:

Also If I am using config 4 (or 2), I am supplying power only to the VDDH, I can take out VDD (1.8 to 3.3 V) from any of the VDD pin, but what I have to do with those remaining VDD_nRF pins and their corresponding capacitors?

Choosing config 4, then you need to only supply power to VDDH rail. But you still need all the decupling caps and VDD rail, as this is used by the internal regulator to supply the rest of the components on the nRF52 microcontroller. 

Sreejith Sundh said:

What is denoted by V_VDDH ?, Lets assume I have to get VDD or VEXT of 3.3V (The highest psooible value) from nRF52840 what would be the VDDH value?

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf52840%2Fpower.html&cp=4_0_0_4_2_0_2&anchor=unique_1706523351 
You can see it in this table.

Sreejith Sundh said:

how can I configure REG0 to get output or VDD of 3.3V? Is there any example (code) to configure REG0 (I am using nRF52840 SoC with S140 and nRF5)?  

Here are two examples on how to set REG0
How to set the vdd level - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) 
nRF52840 regulator configuration - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) 

Sreejith Sundh said:

I refered to nRF52840 DK schematic, and found that they uses switches along with reverse protection circuit.

Yes, you can use the nrf52840 DK or the Thingy52/91 as a reference for a protection circuit.  


Regards,
Jonathan

[Sreejith Sundh]

Hi,

II would like to check with my schematics, I hereby attaching screenshot of my schematic, I want to use 4GPIO pins as my sensor interfaces, 1 GPIO pins as LED (Connection indication) I selected Reference circuitry Config No. 5 without USB (I do not have power supply). Is this schematic fine?

JONATHAN LL said:

We do help with HW layout and Schematic, and we do reviews of design, so feel free to ask for a review of you circuitry when you have put something together. 

How can I apply for review of my design? I would like to get this support. 

Thanks Jonathan

With Regards,

Sreejith

[JONATHAN LL]

Sreejith Sundh said:

How can I apply for review of my design? I would like to get this support. 

You can create a new public or private Devzone ticket, name it something like "Schematic and Hardware review request, nRFXX" and we will provide all feedback there. If you don't minds sharing your project then you can create a public ticket, if you don't want to share then make a private one. 

This way we keep everything related to your specific question in that ticket. And general inquiries like you have here can be uncluttered. This way it is easier for others to find the correct and useful info in our forums. 
 
We move the discussion about your specific schematic over to the Review ticket. But looks OK. 

Regards,
Jonathan