-0.60

-0.50

-0.40

-0.30

-0.20

-0.10

0.00

0.10

0.20

0.30

0.40

0.50

0.60

±60 ±40 ±20

0

20

40

60

80

100 120 140 160

DUT Temperature (

ƒC)

C015

Max Limit when

using LUT

Min Limit when

using LUT

Max Limit when

using Equation

Min Limit when

using Equation

LMT70, LMT70A

www.ti.com

SNIS187A – MARCH 2015 – REVISED JULY 2015

Figure 32. Using Second Order Transfer Function Best Fit -10°C to 110°C

10.2.2.2 ADC Requirements

The ADC resolution and its specifications as well as reference voltage and its specifications will determine the

overall system accuracy that you can obtain. For this example the 12-bit SAR ADC found in the MSP430 was

used as well as it's integrated reference. At first glance the specifications may not seem to be precise enough to

actually be used with the LMT70 but the MSP430 ADC and integrated reference errors are actually measured

during production testing of the MSP430. Values are then provided to user for software calibration. These

calibration values are located in the MSP430A device descriptor tag-length-value (TLV) structure and found in

the device-specific datasheet. The MSP430 Users Guide includes information on how to use these calibration

values to calibrate the ADC reading. The specific values used to calibrate the ADC readings are:

CAL_ADC_15VREF_FACTOR, CAL_ADC_GAIN_FACTOR and CAL_ADC_OFFSET.

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