TMP112
www.ti.com ......................................................................................................................................................... SBOS473B–MARCH 2009–REVISED JUNE 2009
EXAMPLE 1: Finding Worst-Case Accuracy From –15°C to +50°C
As an example, if the user is concerned only about the temperature accuracy between –15°C to +50°C, the
worst-case accuracy could be determined by using the two slope calculations of Equation 2 and Equation 4:
AccuracyMAX (-15°C to 25°C) = Accuracy(25°C) + DT ´ Slope1MAX
(2)
m°C
AccuracyMAX (-15°C to 25°C) = 0.3°C + (-15°C - 25°C)
-7
= +0.58°C
°C
(3)
(4)
AccuracyMAX (25°C to 50°C) = Accuracy(25°C) + DT ´ Slope2MAX
m°C
AccuracyMAX (25°C to 50°C) = 0.3°C + (50°C - 25°C) ´
5
= +0.425°C
°C
(5)
(6)
The same calculations must be applied to the minimum case:
AccuracyMIN (-15°C to 25°C) = Accuracy(25°C) + DT ´ Slope1MIN
m°C
AccuracyMIN (-15°C to 25°C) = -0.5°C + (-15°C - 25°C)
0
= -0.5°C
°C
(7)
(8)
AccuracyMIN (25°C to 50°C) = Accuracy(25°C) + DT ´ Slope2MIN
m°C
AccuracyMIN (25°C to 50°C) = -0.5°C + (50°C - 25°C)
0
= -0.5°C
°C
(9)
Based on the above calculations, a user can expect a worst-case accuracy of +0.58°C to –0.5°C in the
temperature range of –15°C to +50°C.
EXAMPLE 2: Finding Worst-Case Accuracy From +25°C to +100°C
If the desired temperature range falls in the region of slope 3, it is necessary to first calculate the worst-case
value from +25°C to +85°C and add it to the change in temperature multiplied by the span error of slope 3. As an
example, consider the temperature range of +25°C to +125°C as shown in Equation 10:
AccuracyMAX (25°C to 100°C) = Accuracy(25°C) + DT ´ Slope2MAX + DT ´ Slope3MAX
(10)
m°C
°C
m°C
°C
AccuracyMAX (25°C to 100°C) = 0.3°C + (85°C - 25°C)
+ (100°C - 85°C)
8
4.5
= +0.690°C
(11)
(12)
(13)
Performing the same calculation for the minimum case is shown in Equation 12:
AccuracyMIN (25°C to 100°C) = Accuracy(25°C) + DT ´ Slope2MIN + DT ´ Slope3MIN
m°C
m°C
AccuracyMIN (25°C to 100°C) = -0.5°C + (85°C - 25°C)
+ (100°C - 85°C)
0
0
= -0.5°C
°C
°C
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