EFM32WG Datasheet, PDF (685/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

28.3.4.2 Temperature Measurement
...the world's most energy friendly microcontrollers
The ADC includes an internal temperature sensor. This sensor is characterized during production and the
temperature readout from the ADC at production temperature, ADC0_TEMP_0_READ_1V25, is given
in the Device Information (DI) page. The production temperature, CAL_TEMP_0, is also given in this
page. The temperature gradient, TGRAD_ADCTH (mV/degree Celsius), for the sensor is found in the
datasheet for the devices. By selecting 1.25 V internal reference and measuring the internal temperature
sensor with 12 bit resolution, the temperature can be calculated according to the following formula:
ADC Temperature Measurement
T_CELSIUS=CAL_TEMP_0-(ADC0_TEMP_0_READ_1V25-
ADC_result)×Vref/(4096×TGRAD_ADCTH)
(28.2)
Note
The minimum acquisition time for the temperature reference is found in the electrical
characteristics for the device.
28.3.5 Reference Selection
The reference voltage can be selected from these sources:
• 1.25 V internal bandgap.
• 2.5 V internal bandgap.
• V_DD.
• 5 V internal differential bandgap.
• External single ended input from Ch. 6.
• Differential input, 2x(Ch. 6 - Ch. 7).
• Unbuffered 2xV_DD.
• The 2.5 V reference needs a supply voltage higher than 2.5 V.
• The differential 5 V reference needs a supply voltage higher than 2.75 V.
Since the 2xV_DD differential reference is unbuffered, it is directly connected to the ADC supply voltage
and more susceptible to supply noise. The V_DD reference is buffered both in single ended and differential
mode.
If a differential reference with a larger range than the supply voltage is combined with single ended
measurements, for instance the 5 V internal reference, the full ADC range will not be available because
the maximum input voltage is limited by the maximum electrical ratings.
Note
Single ended measurements with the external differential reference are not supported.
28.3.6 Programming of Bias Current
The bias current of the bandgap reference and the ADC comparator can be scaled by the BIASPROG,
HALFBIAS and COMPBIAS bit fields of the ADCn_BIASPROG register. The BIASPROG and HALFBIAS
bitfields scale the current of ADC bandgap reference, and the COMPBIAS bits provide an additional
bias programming for the ADC comparator as illustrated in Figure 28.5 (p. 686) . The electrical
characteristics given in the datasheet require the bias configuration to be set to the default values, where
no other bias values are given.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
685
www.energymicro.com