At a high level, the EFR32 series 1 chip has two major blocks: MCU + Radio.
By default, most of the applications use EFR32 series 1 chip for both its MCU and radio functionality, but there are certain applications where the designer might want to use the EFR32 chip as an MCU only device i.e. without radio functionality. A reason for such usage would be due to some features that other MCUs might not have or to simply keep the application future proof with the possibility of wireless capability.
In the case where the radio is not used, special care needs to be taken to connect and configure the part properly.
The table below provides a comparison of generic pin connections for the standard EFR32 with radio used versus the non-radio use case:
|EFR32 Pin||Series 1 (Recommended Connection) – EFR32xG1 / xG12 / xG13 / xG14|
|Radio is Used||Radio is not used*|
|VREGVDD||Main Supply||Main Supply|
|AVDD||Main Supply||Main Supply|
|Internal DC-DC is used||Internal DC-DC is not used||Internal DC-DC is used||Internal DC-DC is not used|
|PAVDD||TX power > +13dBm||Main Supply||Main Supply||DVDD||Main Supply|
|TX power <= +13dBm||DVDD||Main Supply|
|RFVDD||DVDD||Main Supply||DVDD||Main Supply|
|DVDD||VREGSW (mandatory)||Main Supply||VREGSW (mandatory)||Main Supply|
|VREGSW||Filtering components required – refer AN948||Left Floating||Filtering components required – refer AN948||Left Floating|
|IOVDD||AVDD or as per Host MCU’s requirement||AVDD or as per Host MCU’s requirement|
|DECOUPLE||1uF capacitor to GND||1uF capacitor to GND|
|2G4RF_IOP||EFR32 matching network – refer AN930.1||Left Floating|
|SUBGRF_OP||EFR32 matching network – refer AN923||Left Floating|
|Unused GPIO||Left Floating||Left Floating|
|RESETn||Debug Header or Host MCU or a Testpoint||Debug Header or Host MCU or a Test point|
* Please note that even if the Radio block of the EFR32 chip is not used, DC voltage should be supplied at the appropriate power supply (PAVDD, RFVDD) pins along with the respective filtering components. A detailed pin connection and filtering component information are given in AN0002.1.
The EFR32 Series 1 Supply constraints are as follows:-