STLM20 temperature-to-output transfer function

AN2648

2/15

1

STLM20 temperature-to-output transfer function

Upon examining the temperature sensor's output characteristics, several issues become

This is rather unwieldy math for a simple 8-bit micro, but a linear approximation is available

which matches the curve very closely. As shown in Figure 2, the dashed blue line is a very

Equation 1

This is much more manageable for coding in assembly language without a math package. In

this figure, the reader will note that the curve deviates only slightly from the line at the

extreme ends. In the middle, they are almost indistinguishable.

Figure 2.

STLM20 transfer function

V

8639

.

1

)

T

10

15

.

1

(

)

T

10

88

.

3

(

V

2

2

6

0

+

×

×

−

+

×

×

−

=

−

−

V

8663

.

1

T

C)

V/

01169

.

0

(

V

0

+

×

°

−

=

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

-60

-40

-20

0

20

40

60

80

100

2nd Order

Linear

ai13986

Temperature, T (˚C)