Our device is resetting. What looks like is happening is that our 3.25A over-current protection system on our power management IC is being triggered. Any current consumption >3.25A will cause our power management IC to cut power to the load (the Notecard and host MCU in this case).
We thought 3.25A would be plenty since the Blues docs say that the Notecard will only consume up to ~2A peak during sync. It’s worth noting that in the years we have been using older notecards, namely NOTE-WBNA-500 (legacy North America Cat-1), we have never seen a current spike over 2A. But when we switched to NOTE-MBGLN (LTE Cat-1 bis | Global), our device started resetting. Below are some screenshots from our Joulescope showing the same device in the same location with the same antenna, but two different Notecards (legacy NOTE-WBNA-500 vs. new NOTE-MBGLN).
What has made this problem more painful to diagnose (and the reason we did not catch it during testing) is that it does not happen all the time. Many times the NOTE-MBGLN syncs with <3A peak current (although it’s close, usually around 2.8A or more), and our product is fine. But now that products are out there in customer’s hands, many of them are in reset doom loops.
Is there anything Blues can do with Notecard firmware to reduce the peak current consumption of NOTE-MBGLN down to the 2A level that is specified in the docs?
