MAX Limit

MIN Limit

Typical

-100

-50

0

50

100

150

-5

-4

-3

-2

-1

0

1

2

3

4

5

TEMPERATURE (ºC)

LM19

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SNIS122E – MAY 2001 – REVISED MARCH 2013

Typical Performance Characteristics

Temperature Error vs. Temperature

Thermal Response in Still Air

LM19 TRANSFER FUNCTION

The LM19'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

VO= −11.69 mV/°C × T + 1.8663 V

(1)

Over the full operating temperature range of

−55°C to +130°C, best accuracy can be obtained by using the

parabolic transfer function

VO = (−3.88×10

−6×T2) + (−1.15×10−2×T) + 1.8639

(2)

solving for T:

(3)

A linear transfer function can be used over a limited temperature range by calculating a slope and offset that give

best results over that range. A linear transfer function can be calculated from the parabolic transfer function of

the LM19. The slope of the linear transfer function can be calculated using the following equation:

m =

−7.76 × 10

−6× T − 0.0115

where

•

T is the middle of the temperature range of interest and m is in V/°C.

(4)

For example for the temperature range of Tmin = −30 to Tmax = +100°C:

T = 35°C

and

m =

−11.77 mV/°C

The offset of the linear transfer function can be calculated using the following equation:

b = (VOP(Tmax) + VOP(T) − m × (Tmax+T))/2

where

•

VOP(Tmax) is the calculated output voltage at Tmax using the parabolic transfer function for VO.

•

VOP(T) is the calculated output voltage at T using the parabolic transfer function for VO.

(5)

Using this procedure the best fit linear transfer function for many popular temperature ranges was calculated in

Table 1. As shown in Table 1 the error that is introduced by the linear transfer function increases with wider

temperature ranges.

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