RD014-RGUIDE-01
2018-03-15
Rev. 1
7
/
19
© 2018
Toshiba Electronic Devices & Storage Corporation
The NL
200
or NL
100
parameter represents the linearity of an isolation amplifier. NL
200
is
calculated as follows:
1. The least-squares method is used to find a line of the best fit that represents the
relationship between the input voltage differential (V
IN+
-V
IN-
) and the output voltage
differential (V
OUT+
-V
OUT-
).
2. The deviations of the output voltage differential (V
OUT+
-V
OUT-
) from the line of the best
fit are calculated.
3. The sum of the absolute values of the maximum and minimum deviations
(|d|dev_min|) is calculated.
4. The ratio of this sum to the full-scale differential output voltage (V
OH
-V
OL
) is calculated.
Figure 2.5 shows the relationship between the input voltage and the output voltage
deviation from the line of the best fit.
Figure 2.5 Input voltage vs. output voltage deviation from the line of best fit
NL
200
is calculated as follows:
%
|
_
|
|
_
|
From Figure 2.5, dev_max = 1.3 mV, dev_min = -1 mV, and V
OH
-V
OL
= 2.5 V, then:
0.0013
0.001
2
2.5
100
0.046%
Equivalent to
NL
200
=0.13%
(maximum rated
value)
V
OH
V
OL
Line of the best fit
& measured
The deviation of the
measured data from the
line of best fit is plotted.
Approximate line
y=ax+b
