Powering nRF52810 with 3.6V Lithium battery

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Fri, 25 Mar 2022 14:18:03 GMT

If I was to guess, I would say that the special capacitors on the DEC-pins are causing the module to be very sensitive. The values for these DEC capacitors are normally not recommendations, they are to be followed strictly. The module manufacturer might have some good reason to deviate though.

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Thu, 24 Mar 2022 16:45:10 GMT

[quote userid="90815" url="~/f/nordic-q-a/86012/powering-nrf52810-with-3-6v-lithium-battery/359859#359859"]As a consequence, BAT_MEAS will reach 3.6V earlier than VCC.[/quote]

There's an RC filter on this pin. R1 12K along with the 100nF capacitor.

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Thu, 24 Mar 2022 16:37:27 GMT

I'm definitely going to correct the capacitance on every power pin of the module

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Thu, 24 Mar 2022 16:36:40 GMT

Indeed. Although it is very strange to me why they state that.

If you look at the picture I posted above you can see that the only active part inside the module is the nRF52810 SoC.

The rest of the circuitries are crystal oscillators, an antenna matching circuit and some capacitors. Nothing that would explain the difference from the SoC datasheet

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Thu, 24 Mar 2022 16:31:17 GMT

Thank you for your help!

I did not notice those extra capacitors. I added them because I wasn't sure about the internal schematic.

I also took a picture of the module

Can you please provide more information regarding the importance of the pins you mentioned?

Regarding the other questions.

[quote userid="90815" url="~/f/nordic-q-a/86012/powering-nrf52810-with-3-6v-lithium-battery/359836#359836"]How is the temp/humid sensor powered? What is the voltage on the I2C pins from the sensor?[/quote]

The temp/humid sensor powered directly from the battery. The voltage on the I2C bus is the same as Vbat. SHT31-DIS-B is the part number.

[quote userid="90815" url="~/f/nordic-q-a/86012/powering-nrf52810-with-3-6v-lithium-battery/359836#359836"]

How is AIN0 configured internally?

Could you please measure AIN0 on both the broken and working units? Is it shorted?

[/quote]

Is it configured to work as analog input pin.

So far, apart from the high percentace of random battery drain on some beacons I have only one dead product in the lab. I checked every pin with a DMM with respect to ground. no one is shorted.

[quote userid="90815" url="~/f/nordic-q-a/86012/powering-nrf52810-with-3-6v-lithium-battery/359836#359836"]Have you measured the battery voltage in various conditions when brand new? Would you be able to share the datasheet for your specific battery?[/quote]

A brand new battery has 3.6V

I think that's its datasheet

https://www.compel.ru/pdf-items/eemb/ps/er14250/854b3cfd8bbc0ca8f0eb7f130ed3f8a8

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 15:52:59 GMT

Looking at chapter 4. and 5.2 in the module's datasheet, the module seems to be quite sensitive. The datasheet also recommends being cautious and "reserve more than 30% of the margin", so this does means operating the module at 3.6V is risky.

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 15:37:41 GMT

[quote user="giorgos3924"]We also added an extra 10uF capacitance[/quote][quote user="giorgos3924"], do you think that this capacitance is enough?[/quote]

According to the schematic you provided, the module already has an internal 10uF capacitor(C19). The recommendation is 4.7uF, so this should be more than enough. The product specification states max. and min. rise times for VCC, so it is a good idea to double check that you are within the range.

Another concern: AIN0 (BAT_MEAS) only has a 0.1uF capacitor. As a consequence, BAT_MEAS will reach 3.6V earlier than VCC. I have not yet checked whether the product specification states that this is OK.

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 15:22:03 GMT

I also had a look at DEC4 in your schematic and in the internal schematic of the module. It looks as a the capacitance at DEC4 also deviates from the recommended values in the reference design. The reference design recommends 1.0uF, however, the module is listed with 100nF. If this is the case, nRF52810 is then provided with 1000nF + 100nF instead of 1000nF.

It is hard to guess exactly what will happen if the capacitance at the DEC pins deviate from the reference design. However, this would be among the most important issues to improve in the design.

You could try to modify one of the working beacons in order to provide the DEC pins with the correct capacitances, although this is difficult when the module already deviates from the recommendations. You could perhaps contact the module manufacturer in order to get their comments on the DEC pins.

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 14:55:01 GMT

[quote user=""]The question is can that battery be used for nRF52810? In the datasheet it says absolute maximum at 3.6V yet in the recommended voltage range it mentions up to 3.6V.[/quote]

Yes, this could be the main issue here. The nRF52810 itself may handle 3.9V max. However, since the datasheet of the module says 3.6V max., then it is important to stay safely below this voltage.

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 14:28:14 GMT

Hi again,

I also noticed that the schematics that you provided for the module has a 100nF capacitor connected to DEC3. The recommended value according to the reference design is 100pF. As far as I know, this could potentially also cause problems. Could you please somehow try to verify that the schematic you provided for the module is showing exactly what is inside the module?

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Thu, 24 Mar 2022 14:18:56 GMT

Thank you for sharing the schematics.

It appears as if you might have doubled the capacitance on DEC1. The reference design for nRF52810 recommends a 100nF capacitor on DEC1. However, both the internal schematics of E73-2G4M04S1A that you posted previously(C18), and your own schematics(C7) shows a 100nF capacitor on DEC1. Using the right capacitance on the DEC pins is highly important. I do not know how doubling the capacitance of DEC1 will effect the circuit, however, at this stage I can not rule out this being the cause of your problem.

Here are a few other thoughts:

[quote user="giorgos3924"]I2C bus and SENSE_ pins are connected to a integrated temp/humid sensor. The sensor can work up to 5.5V[/quote]

How is the temp/humid sensor powered? What is the voltage on the I2C pins from the sensor?

BAT_MEAS

How is AIN0 configured internally?

Could you please measure AIN0 on both the broken and working units? Is it shorted?

[quote user=""]ER14250 3.6V Lithium battery, 1200mAh[/quote]

Have you measured the battery voltage in various conditions when brand new? Would you be able to share the datasheet for your specific battery?

A picture of your PCB or a report from when you are visually inspecting your PCB would still be interesting to hear about.

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Wed, 23 Mar 2022 14:45:45 GMT

Hi helsing,

Below you can see the rest of the schematic

I2C bus and SENSE_ pins are connected to a integrated temp/humid sensor. The sensor can work up to 5.5V

The rest of the pins you see on the schematic are not connected anywhere.

I could not find any reason the module died.

Do you think the total capacitance on the power rail is enough for the transmission peaks?

Also, I checked with an oscilloscope the current consumption during transmission and the results are very similar to what I see on

devzone.nordicsemi.com/.../online-power-profiler-for-bluetooth-le

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Tue, 22 Mar 2022 10:18:18 GMT

Hi george

[quote user="giorgos3924"]We also added an extra 10uF capacitance.[/quote]

Where did you add this capacitor?

[quote user="giorgos3924"]Below you can see its internal schematic.[/quote]

Thanks. Would you be able to share anything from the external schematic?

[quote user="giorgos3924"]What do you think would cause that damage to the module?[/quote]

Since not all devices are failing, I would start by visually inspecting the hardware assembly and check the soldering. It would also be interesting to know more about the rest of your unit. Have you done any comparison between the failing beacons with the ones which are not failing? What is the current consumption of the units which are not failing? How much current is drawn in the various operating modes? PPKII is a great tool for these type of measurements.

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Mon, 21 Mar 2022 13:47:27 GMT

It is not rechargable. The battery has 3.6V brand new.

RE: Powering nRF52810 with 3.6V Lithium battery

PaKa — Mon, 21 Mar 2022 13:46:46 GMT

Please do note that a rechargeable Li-Ion battery marked 3.6V normally comes with a fully charged voltage of 4.1V to 4.2V (3.6V is the average value during the discharge curve). This means that you can't use any such batteries with the 3.6V nRF5 devices. Any devices that have been attached to such a battery should be considered broken.

RE: Powering nRF52810 with 3.6V Lithium battery

George555 — Mon, 21 Mar 2022 11:51:38 GMT

Hi helsing,

The beacon board is based on a chinese module E73-2G4M04S1AX of Ebyte

Below you can see its internal schematic.

The version we have makes use of an nRF52810 with an external BLE antenna attached to it. We also added an extra 10uF capacitance.

I also use the integrated DC/DC after following the reference circuit.

First, do you think that this capacitance is enough?

Second, What do you think would cause that damage to the module? I mentioned again that it was found dead after a week.

RE: Powering nRF52810 with 3.6V Lithium battery

helsing — Mon, 21 Mar 2022 10:12:16 GMT

Hi george,

Edit: A 3.6V battery voltage should normally not cause any problems. (However, as Pål points out, a 3.6V rechargeable battery could potentially be charged to a higher voltage.)

Table 131 on page 410 in the product specification for nRF52810 specifies VDD max. to +3.9V.

Would you be able to share the schematics for your design?

Have you inspected the boards for any assembly errors? Would you be able to share a photo of the board?