Brownout issue

The XBee 3 RF Module uses a Silicon Labs EFR32MG System on Chip (SoC). Silicon Labs has announced an intermittent restarting issue with EFR32MG revision B SoCs which can be caused by voltage brownout or supply dips during power-on. The information below is provided to help you avoid this condition.

Voltage brownout

This issue may occur if the supply powering the XBee VCC pin dips momentarily into the range of approximately 1.2 to 1.8 V. When the supply returns to normal levels the SoC may not restart properly and enter an unresponsive state. You must fully power cycle the XBee to recover from this state. The failure rate tends to increase with slower ramp down rates of the power supply; for more details see RMU_E203 — AVDD Ramp Issue. If you keep the power supply within the operational voltage range specified in Power requirements, the conditions to cause this failure are never met.

Power-on discontinuities

This issue is similar to the voltage brownout issue. The SoC may fail to start if, during power on, the supply powering the VCC pin experiences discontinuities in the voltage rise (in other words, dips) while the voltage is in the range of approximately 1.2 to 1.8 V. You must fully power cycle the XBee 3 Cellular LTE-M/NB-IoT to recover from this state. The failure rate tends to increase with slower ramp up rates of the power supply; for more details see RMU_E203 — AVDD Ramp Issue. The issue can be avoided by ramping your power supply steadily to the normal operating range.

How to distinguish revision B parts

Silicon Labs has corrected these issues in revision C of their SoC. We are printing the SoC revision on the XBee label to make it easy to distinguish. The revision letter is located on the bottom right corner of the product label.