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DS1868

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ABSOLUTE AND RELATIVE LINEARITY

Absolute linearity is defined as the difference between the actual measured output voltage and the

expected output voltage. Figure 5 presents the test circuit used to measure absolute linearity. Absolute

linearity is given in terms of a minimum increment or expected output when the wiper is moved one

position. In the case of the test circuit, a minimum increment (MI) or one LSB would equal 5/256 volts.

The equation for absolute linearity is given as follows:

(1) ABSOLUTE LINEARITY

AL={V

(actual) - V

(expected)}/MI

Relative linearity is a measure of error between two adjacent wiper position points and is given in terms

of MI by equation (2).

(2) RELATIVE LINEARITY

RL={V

(n+1) - V

(n)}/MI

Figure 6 is a plot of absolute linearity and relative linearity versus wiper position for the DS1868 at 25°C.

The specification for absolute linearity of the DS1868 is ±0.75 MI typical. The specification for relative

linearity of the DS1868 is ±0.3 MI typical.

LINEARITY MEASUREMENT CONFIGURATION Figure 5

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