CC2650 no reasonable Temperature Data

I've tried to read the temperature value from the temperature sensor integrated in the CC2650F128 controller.Unfortunately I am only receiving three different values (see below for actual values).
I can reproduce these values with two different CC2650F128 controllers.

Here's my simplified code for reading the temperature value:

#include <driverlib/aon_batmon.h>

// ...

AONBatMonEnable();
AONBatMonMeasurementCycleSet(AON_BATMON_CYCLE_CONT);

if(AONBatMonNewTempMeasureReady()) {

AONBatMonTemperatureGet();

} else {

// Try again next cycle

}

AONBatMonDisable();

I use the default TrimSet at 3,3 Volt.

I received the following values from the device:

AONBatMonTemperatureGet()      ???,  90,     105

AON_BatmonTempGetDegC()     ???,  0x17, 0x1A         

in °C                                                    19.5, 22.5, 26.25