Does pin RESET wake EFM32PG from EM4S mode if IOVDD is powered by the DC-DC regulator?

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 04:25 PM

Question

The Pearl Gecko reference manual states for Power Configuration 2 (DC-DC) of the EMU chapter: "IOVDD could be connected to either the main supply (as shown below) or to VDCDC, depending on the system IO requirements."  If I connect IOVDD to VDCDC, will a pin reset still wake the device from EM4 Shutoff (EM4S)?  This seems unlikely, since the DC-DC is not available in EM4S so VDCDC will be unpowered.

Answer

The integrated DC-DC on EFM32 Pearl Gecko is indeed unavailable while in EM4S.  However, VDCDC is still powered while in EM4 Shutoff.  In your example, IOVDD will also then be powered in EM4S, so a pin RESET is still detectable.

 

This result arises from the fact that in EM4 Shutoff, the DC-DC converter configuration is reset to its default Startup configuration (DC-DC converter disabled, bypass switch is on), in which the VREGVDD input voltage is directly shorted to the DC-DC converter output through an internal switch. Consult the datasheet for more information on the Bypass switch impedance specification.