NB-iot shield: Power requirements and power usage

Hello.

I am starting out with testing my nb iot shield. I have connected it as a shield on top of my Arduino Leonardo, and got it working with the serial passthrough example. The Arduino is powered with usb from my computer.

My questions are as follows:

  1. Will USB provide sufficient power at max 500 mA?
  2. What are the highest peak currents to be expected?

The SARA N2 data sheet lists 250 mA TX current, averaged over 2 seconds. The peaks may be way higher than 250 mA, with GPRS it can be up to 2000 mA. Is there any capacitor on the SODAQ nb iot shield that will handle current peaks during Transmission?

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Hi Anders,

The power that the USB will provide is sufficient. Although the datasheet isn’t really clear about the peak current consumption, the System Integration Manual shows the following graph (which I’m assuming is at 23dBm):

The GPRS-modules (SARA-G3) can indeed reach current peaks up to 2A, which is why we prefer to connect a battery directly to the Vcc in those cases. However, the SARA-N2 modules will never reach those currents. To be safe and catch some of the peaks, we placed a tantalum capacitor at the voltage input of the SARA-N2xx.

Hope this helped you!

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Just what i needed, thanks!
Can you share a link to where this data is found?

Hi Anders,

Unfortunately we cannot share the System Integration Manual with you (as we got these under NDA). However, you might be able to get this by contacting uBlox directly. All the ‘open’ datasheets and manuals for the SARA-N2 can be found here: https://www.u-blox.com/en/product-resources?f[0]=property_file_product_filter%3A14722

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