Expected current draw of nPM1100 EK

[Gary T]

Hi Nordic Team

I have purchased an nPM1100 EK to evaluate the inclusion of an nPM1100 in an IoT project I am busy with.

I am measuring the current draw using a PPK2 connected as per the diagram shown in the nMP1100 EK User Guide (5.4.2 Measuring VBAT current). The output from the PPK2 is connected to the VBAT_HF pin.

The only difference is that I have connected a multimeter to VOUTB to measure the output voltage. There is no device connected to the output other than the multimeter.

In section 5.1  of the user guide (Preparing the nPM1100 EK) is says "Changes are not needed when using the PPK2" so I have not cut any of the bridges.

In order to measure the current, I set the PPK2 to 4V and activated "Source meter" mode.

Once activated, the multimeter reads just over 3V as expected but the PPK2 shows current of 3.5mA.

If I active shipping mode then it goes down to 0.5µA.

I am wondering why it is consuming so much current when active. 3.5mA seems excessive? Is this expected?

Have I misunderstood the User Guide instructions by not cutting any of the bridges?

Thanks for your help.

Regards

Gary

[Gary T]

Hi Sigurd

Initially, I wasn't using any load. I had just connected the multimeter.

I have subsequently tested with 2 different devices.

The first is a nRF9160 DK. When sleeping and connected directly to the PPK, the DK uses 844µA. If I connect it via the nPM1100 DK the sleep usage is 4.17mA. (4.170mA - 0.844mA = 3.3mA).

The second is a nRF52840 Dongle transmitting a Bluetooth beacon. The average current usage when connected directly to the PPK2 is 17µA. When I connect it via the nPM1100 DK the average is 3.55mA.

I have attached a picture to show the wiring.

Regards,

Gary

[Sigurd]

Hi,

Please try to set the SW1 MODE to GND

https://infocenter.nordicsemi.com/topic/ug_npm1100_ek/UG/nPM1100_EK/buck_converter_mode.html?cp=7_0_2_3_4_3

https://infocenter.nordicsemi.com/topic/ps_npm1100/chapters/core_components/buck/doc/frontpage.html?cp=7_0_0_5_2_1#buck_mode_selection

For low currents it has better efficiency in Auto mode.

https://infocenter.nordicsemi.com/topic/ps_npm1100/chapters/core_components/buck/doc/frontpage.html?cp=7_0_0_5_2_4#elec_chara