https://devzone.nordicsemi.com/f/nordic-q-a/29330/nrf52840-ic-marking-questionHi Nordic Engineers! we bought 110 nRF52840 IC&#39;s for Field tests. 10 of them marked Q1AAAA / 1716AK another 100 marked Q1AABB / 1745AC What is difference between series ? Why AAAA works but AABB all fail ?en-USTelligent Community 13Wed, 10 Jan 2018 12:01:31 GMThttps://devzone.nordicsemi.com/thread/116691?ContentTypeID=1Wed, 10 Jan 2018 12:01:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:4af626bd-56a7-421c-94db-784353172ca4MartinBL<p>As @endnode says, QIAAAA is Engineering A and QIAABB is Engineering B. Unfortunately there is a small, but important change to the reference design of the QIAABB. Please see this thread: <a href="https://devzone.nordicsemi.com/question/186260/nrf52840-q1aabb-ble-advertising-problem/?answer=186387#post-id-186387">nrf52840 Q1AABB ble advertising problem</a>.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/116692?ContentTypeID=1Wed, 10 Jan 2018 11:44:06 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a3d5652b-9dee-4dde-b427-d35c9639cd73endnode<p>(Not being Nordic engineer I will still dare to answer): <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52/dita/nrf52/compatibility_matrix/nRF52840_ic_revision_overview.html?cp=2_0_2_0">read the documentation!</a> One is nRF52840 Engineering RevA, second is RevB. None of them is production Rev1 (not officially released yet).</p><div style="clear:both;"></div>