Datasheet

Transfer function STLM20
6/19 Doc ID 12495 Rev 13
2 Transfer function
The STLM20’s transfer function can be described in different ways, with varying levels of
precision. A simple linear transfer function, with good accuracy near 25 °C is expressed as:
Equation 1 (first order linear equation)
Over the specified operating temperature range, the best accuracy can be obtained by using
the parabolic transfer function:
Equation 2 (second order parabolic equation)
and solving for T:
The best fit linear transfer function for many popular temperature ranges was calculated in
Table 2 , where the error introduced by the linear transfer function increases with wider
temperature ranges.
Table 2. First order equations optimized for different temperature ranges
Temperature range
Linear equation
V
O
=
Maximum deviation of linear
equation from parabolic equation
(°C)
T
min
(°C) T
max
(°C)
–55 130 –11.79 mV/°C * T + 1.8528 V ±1.41
–40 110 –11.77 mV/°C * T + 1.8577 V ±0.93
–30 100 –11.77 mV/°C * T + 1.8605 V ±0.70
–40 85 –11.67 mV/°C * T + 1.8583 V ±0.65
–10 65 –11.71 mV/°C * T + 1.8641 V ±0.23
35 45 –11.81 mV/°C * T + 1.8701 V ±0.004
20 30 –11.69 mV/°C * T + 1.8663 V ±0.004
V
O
11.69mV–()°CT1.8663+×⁄ V=
8639.1)T1015.1(–)T1088.3(–V
2–26
O
+××+××=
−
()
6–
O
6
1088.3
V8639.1
101962.296.1481–T
×
−
+×+=