Power consumption on the 9160DK board is higher than spec?

[Trung Nguyen]

Hi everyone,

I'm currently working on measuring the power consumption of the 9160DK board and following the guide: Getting started with current measurements on the nRF9160 - nRF9x - Hardware design, test and measuring - Nordic DevZone. My setup follows the SMU mode described in the guide, but instead of using the Power Profiler Kit, I’m utilizing the Joulescope JS110.

In the guide, the author mentions that the floor current of the UDP sample is 2.7µA, and my goal is to replicate this measurement. However, despite following the setup, my lowest recorded value is 3.6µA.

I would appreciate any insights on:

• Possible adjustments to my setup to further reduce the current.
• Explanations for why my measured value differs from the guide’s specifications.

Additional Information:

• SDK Version: v2.9.1
• Network Type: NB-IoT
• Input Voltage: 3.3V

Any suggestions or advice would be greatly appreciated!

[Charlie]

Hi,

Thanks for checking with us regarding your questions.

I double-checked the nRF9160 Product Specification, and it states that the voltage reference for power consumption is 3.7 V.

Current consumption @ 3.7 V:

• Power saving mode (PSM) floor current: 2.7 µA

Please note that the PSM current listed is a typical value. Some variation is expected, so we recommend measuring multiple devices for a more accurate evaluation.

Best regards,

Charlie

[Trung Nguyen]

Thank you for your response. I have a few follow-up questions related to RAM power consumption:

1. The Cellular UDP sample documentation does not clearly state whether RAM is retained during operation. Based on the context, I assume that RAM retention is enabled—could you please confirm?

2. I understand that the sample only uses a small portion of the available RAM. Is the entire RAM retained in this case, or only the regions that are actively used?

3. According to the Product Specification, the RAM leakage current is 100 nA per 32 KB block. Let’s consider three RAM states:

   • ON (actively used when the CPU is running)

   • Retained (while the CPU is idle)

   • OFF (completely powered down)

   I assume the specified leakage current applies to RAM blocks in the OFF state. Is that correct? Additionally, is there documentation available that specifies the current consumption for RAM blocks in the retained state?

And does the network configurations or signal strength have any affection on the device's power consumption while the LTE modem is in PSM mode?

Thanks again for your support.

[Charlie]

Hi,

Please refer to the following reply:

1. all application RAM is retained.
2. all application RAM is retained, needs to use the RAM power API to turn off unused RAM.
3. Specified leakage is for ram retention. When powered down it does not consume any current.
4. network config and signal strength does not have an impact on PSM current.

Best regards,

Charlie