DA6512.003
2 December, 2016
TEMPERATURE MODE
The MAS6512 has an internal temperature sensor
for temperature measurement. The temperature
sensor output is proportional to absolute
temperature (PTAT). The temperature information
is needed for temperature indication and
temperature compensation.
already the smallest over sampling ratio (OSR)
selection 256 offers sufficient resolution for the
temperature measurement.
The internal temperature sensor has offset and gain
variation but small non-linearity (see Electrical
Characteristics table). Depending on temperature
measurement accuracy requirement the offset, the
gain and the non-linearity all can be compensated
by external calculations. In low precision the offset
and gain calibration is sufficient but in high precision
the second order non-linearity calibration can be
included.
The temperature measurement is started by writing
configuration data to the measurement control
register
(E2/62HEX).
In
the
temperature
measurement the internal regulator has to be
enabled (TEMPREGEN=1) and the internal
temperature sensor selected (SEL=10). The ratio
and difference converter bit (XRC) selection does
not have any influence on the result. Typically
Linear temperature sensor model
The linear temperature measurement model for output code is following.
CODE CODEFS
a b
T TREF
The OSR selects full scale output code range value CODEFS. See Electrical Characteristics for CODEFSDIFF at
different OSR values. If the temperature T is presented in °C and referenced to TREF=0°C then the typical
linearized temperature sensor model parameter values a and b are as follows.
a=0.38944
b=4.4329e-3
However it should be noted that the sensor has significant offset (parameter a) variation and also the gain
(parameter b) has some variation and that the above values represent only typical values. The non-linearity
temperature error after offset and gain calibration (best fit line) is typically <±0.5°C in the temperature range -
40°C…+85°C.
2nd order temperature sensor model
For higher precision the 2nd order temperature measurement model for output code is following
2
CODE CODEFS
a b
T TREF
c
T TREF
If the temperature T is presented in °C and referenced to TREF=0°C then the typical 2nd order temperature sensor
model parameter values a, b and c are as follows.
a=0.38826
b=4.3967e-3
c=8.1098e-7
Above sensor model parameters are typical values which are subject to variations. The temperature error after
offset, gain and 2nd order non-linearity calibration is typically <±0.1°C in the temperature range -40°C…+85°C.
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MAS [ MICRO ANALOG SYSTEMS ]
