Power supply and temperature monitoring

nRF93M1 continuously monitors input voltage and internal temperature, and reports threshold events to the host over the AT command interface.

Voltage monitor

Input voltage at the VDD pin and temperature are exposed to the host through the %ADC AT command.

AT%ADC="vbat" returns the current input voltage in mV
AT%ADC="temp" returns the current internal temperature in °C
AT%ADC="all" returns both values

Power alarms

Alarms are received through %PALARM for the following:

%PALARM: Volt,<voltAlarm> and %PALARM: Therm,<thermAlarm>
Where <voltAlarm> - 0-1, Voltage alarm state. 0 means the voltage is below 2.8 V and 1 means voltage level has recovered.
Where <thermAlarm> 0-1, Die temperature alarm state. 0 means the die temperature is below the threshold and 1 means temperature is above the threshold.

The alarm is triggered when one of the following thresholds are reached:

Voltage drops below 2.8 V
Die temperature is above 100°C

Note: %ADC and %PALARM monitoring are available in System ON active operation only. The ADC and monitoring domains are powered down during power-saving sleep.

An application that must monitor supply voltage or temperature continuously has to perform that monitoring from the host MCU.

Under-voltage lockout

If the VDD pin input voltage falls below the minimum operating voltage, the module transitions to minimum functionality. The host must issue +CFUN to restore full functionality. See the Recommended Operating Conditions chapter for supply voltage limits.