AD590IH View Datasheet(PDF) - Intersil

Part Name

Description

Manufacturer

AD590IH

2-Wire, Current Output Temperature Transducer

Intersil 

AD590

Trimming Out Errors

The ideal graph of current versus temperature for the AD590

is a straight line, but as Figure 1 shows, the actual shape is

slightly different. Since the sensor is limited to the range of

-55oC to 150oC, it is possible to optimize the accuracy by

trimming. Trimming also permits extracting maximum

performance from the lower-cost sensors.

The circuit of Figure 2 trims the slope of the AD590 output.

The effect of this is shown in Figure 3.

The circuit of Figure 4 trims both the slope and the offset.

This is shown in Figure 5. The diagrams are exaggerated to

show effects, but it should be clear that these trims can be

used to minimize errors over the whole range, or over any

selected part of the range. In fact, it is possible to adjust the

I-grade device to give less than 0.1oC error over the range

0oC to 90oC and less than 0.05oC error from 25oC to 60oC.

35.7kΩ

R1 2kΩ

+10V

97.6kΩ R2 5kΩ

+

AD590

-

VOUT = 100mV/ oC

V-

R1 = OFFSET

R2 = SLOPE

FIGURE 4. SLOPE AND OFFSET TRIMMING

IDEAL

ACTUAL

(GREATLY

EXAGGERATED)

T (oK)

FIGURE 1. TRIMMING OUT ERRORS

+5V

+

+

-

AD590

+

R 100Ω

950Ω

VOUT = 1mV/oK

R = SLOPE

FIGURE 2. SLOPE TRIMMING

FIGURE 5A. UNTRIMMED

FIGURE 5B. TRIM ONE: OFFSET

IDEAL

ACTUAL

TRIMMED

T (oK)

FIGURE 3. EFFECT OF SLOPE TRIM

12-5

FIGURE 5C. TRIM TWO: SLOPE

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