nRF9160 resets after lte_lc_connect()

RE: nRF9160 resets after lte_lc_connect()

helsing — Thu, 04 Jan 2024 14:50:52 GMT

[quote user="Bernhard"]I have measured the VDD and in the reset case I observed a drop from 3,3V to 2,8V.[/quote]

Interesting, now you know the reset cause and just need to prevent the voltage from dropping below 3.0V.

[quote user="Bernhard"]the circuit is able to handle additional currents of up to ~ 500mA without a reset or such VDD drops below 3,0V.[/quote]

Have you tried to add the resistor after the board was powered and up and running? Will this make nRF9160 reset? From my understanding of such issues with battery voltage drops: The battery might be able to maintain the voltage level with a larger and stable load (than, say, 500mA), however, it might not be able to maintain the voltage level during a sudden increase in current consumption, without the voltage dropping.

RE: nRF9160 resets after lte_lc_connect()

Bernhard — Mon, 01 Jan 2024 11:28:29 GMT

I have now also managed to measure the current consumption during the reset with power profiler:

Additional current is around 450mA, total current is already in the range of the maximum USB (2.0) current.

RE: nRF9160 resets after lte_lc_connect()

Bernhard — Sat, 30 Dec 2023 14:24:21 GMT

Hello helsing,

it really lools like a problem with the supply, although I do not fully understand why.

I have measured the VDD and in the reset case I observed a drop from 3,3V to 2,8V.

For my understanding the maximum additional current from modem should be around 300mA (or for extreme conditions - which I currently dont have - around 400mA).

I have tested the VDD against additional load currents (by plugging on resistors) but the circuit is able to handle additional currents of up to ~ 500mA without a reset or such VDD drops below 3,0V.
Also from design perspective such currents should be no problem for the circuit.

[quote userid="90815" url="~/f/nordic-q-a/106828/nrf9160-resets-after-lte_lc_connect/461442"]Is the design powered from a battery?[/quote]

Although the device is powered from a battery it is also possible to operate (or load the battery) via USB, which is what we are doing most of the time in the lab and resets are also occuring in this case.

Is there anything we are missing here, are there cases were the current consumption may me higher than that?

RE: nRF9160 resets after lte_lc_connect()

helsing — Thu, 21 Dec 2023 13:19:21 GMT

[quote user=""]We are currently checking the schematic, layout and population - but anyway, our expectation would be that if there were problems at this point, we should only achieve poor connection quality - but in any case no resets.[/quote]

Is the design powered from a battery? If the network sees that your signal is weak, it could ask UE to increase the power. If your power design does not handle the increased current, a voltage drop could cause the unit to reset. Could you try to measure VDD with an oscilloscope in the situation where the unit resets?

[quote user=""]The problem only occurs with the P822601 antenna, not with a 0830AT54A2200E (which is a second population option in the layout).[/quote]

Which frequency bands is the antenna design optimized and tuned for? If 0830AT54A2200E is tuned to more in favor of band 8 than P822601 is, then that could strengthen the hypothesis of a battery/power issue.

RE: nRF9160 resets after lte_lc_connect()

helsing — Thu, 21 Dec 2023 12:51:56 GMT

[quote user=""]We are currently checking the schematic, layout and population [/quote]

If you like, Nordic could also check the schematic and layout of the Nordic related part of the design as a free service. The ticket can be made private in case you do not want to share the design files publicly.

RE: nRF9160 resets after lte_lc_connect()

helsing — Thu, 21 Dec 2023 10:43:05 GMT

Hi Bernard, just letting you know we have started working on this.

Best regards,

Håkon