DC-DC Current Consumption vs. Power Consumption

by <a href="http://community.silabs.com/t5/Welcome-and-Announcements/Community-Ranking-System-and-Recognition-Program/m-p/140490#U140490"><font color="#000000"><font size="2">Hero Employee</font></font> </a> PhillipB on ‎12-28-2016 04:24 PM


From Tables 4.5 ("Current Consumption 3.3V without DC/DC"), 4.6 ("Current Consumption 3.3V with DC-DC"), and 4.7 ("Current Consumption 1.85V without DC/DC") of the EFM32PG1 datasheet, it seems that the current consumption is less when using a 3.3V supply and the internal DC DC converter, than when using a much smaller 1.85V supply and disabling the internal DC DC converter.  This makes no sense to me - is it a datasheet error?


This observation regarding the datasheet current consumption specifications is common, but the specs are indeed correct. Often, the missing key consideration is that though these tables depict current consumption, actual power consumption (dissipation) is a function of both the current consumed and the applied voltage.


For example, the current consumption values in the "1.85V w/out DC-DC" table, when multiplied by 1.85V, yield lower power consumption than the smaller values in the "3.3V with DC-DC" table multiplied by a larger 3.3V supply. Power consumption is even higher in the 3.3V system that does not use the DC-DC.