DK Li-Po battery

[Roger]

Dear All,

I would like to order Li-Po batteries for my nRF52840 development kits and need some information. From the battery, what type of female battery connector is needed to plug into the board?

Kind regards,

Roger

[Roger]

I connected an external battery to Li-Po connector and switched SW9 to Li-Po position with SW6 to default. The battery potential is 4.2V when fully charged. I noticed the leds on the DK appears much more dimmer (barely visible) compared to when supplied by the coin cell battery (3V) or the USB supply (5V). Just a bit strange, is this normal?

I read that in the Li-Po position, the high voltage regulator of the SoC is directly supplied by the Li-Po battery and that the VDD voltage can be set by firmware? Please see this link on page 20.

[AmbystomaLabs]

You are correct. The REOUT0 registers allows you to set the value of VDD. Without know what code you are running, I can't help you out with setting REGOUT0. Also, according to the spec if you leave sw9 in it's normal position then the LiPo is routed through the 5V buck/boost and a fixed 3V buck converter will drive VDD. Then you don't have to worry about setting REGOUT.

[AmbystomaLabs]

According to the spec the default is 1.8V. You can confirm this with a DMM by measuring vdd.

[Roger]

Yes, measured 1.8V over VDD when SW9 is in the Li-Po position and 3V in the VDD position when connected to the coin cell battery. I'm just wondering if the low voltage 1.8V supply will affect the radio transmitting range? The Vdd nominal voltage of the SoC is specified at 3V. At the moment I have the TX output set at 0 dBm and eventually would like to take it up to +4 dBm. I'm running the OpenThread examples.

[AmbystomaLabs]

The RF core is only 1.3V. 1.8V is well above its spec. Plus the brown out reset keeps the nRF from operating if VDD is too low.