https://devzone.nordicsemi.com/f/nordic-q-a/65164/modem-psm-cycle-separate-to-cpu-sleepHi all, I&#39;ve been recently working on PSM for my device, and I&#39;ve not found any resources that answer my query or provide the knowledge I need. From my reading in this article , #6.1. Its suggested that a device can request a long TAU, and make a requesten-USTelligent Community 13Tue, 25 Aug 2020 07:32:01 GMThttps://devzone.nordicsemi.com/thread/266104?ContentTypeID=1Tue, 25 Aug 2020 07:32:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0e606e2c-ca3b-440d-9243-6134ae37ef2aCarl Richard<p>Hello, Nevera!<br /><br />Thank you for the question! You are not the only one that is confused by this. Your desired behavior is indeed possible as the modem does operate separately from the processor. I.e. the modem won&#39;t wake from PSM before the process explicitly tells it so or the timer runs out. However, as Bjørn says you will not be able to enter the &quot;System-Off&quot; mode and still stay connected to the network, but I believe PSM should be adequate.<br /><br />You should take a look at this&nbsp;<a href="https://devzone.nordicsemi.com/nordic/cellular-iot-guides/b/hardware-design/posts/measuring-psm-idle-current-on-the-nrf91-dk">blog post</a>&nbsp;and this <a href="https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/measuring-psm-sleep-current-on-the-nrf9160-dk">blog post</a>, which&nbsp;both describes how to achieve low power operation using PSM. The example code from the former uses a transmission timer that is set to the same as the PSM interval, but that timer can be changed to any desired value (and you can request a much longer PSM timer).&nbsp;</p> <p>Hope this helps and do say if you need any more help!<br /><br />Best regards,&nbsp;<br />Carl Richard</p><div style="clear:both;"></div>