ACCURACY
3-6
C + D ACCURACY
Accuracy of C = ± [A x Ki x Kv + (Kh + Kl) x 100] %
A
=
Basic Capacitance Accuracy
Factor from graph.
For D > 0.1, multiply the basic
accuracy factor by (1 + D).
If the unit is in the constant voltage
(CV) mode or under internal or
external bias, double the basic
accuracy factor.
Ki = Integration Time Factor (see Ki
Table below)
Kv
=
Voltage Error Factor (see Kv table
below).
Kh, Kl
=
Extreme Range Error Term (see
Kh, Kl table below).
Accuracy of D = ± [Ac / 100]
Ac
=
the accuracy of the capacitance
measurement (above)
Note that the accuracy of D is specified as a
magnitude, NOT as a percent.
Ki Table
Meas Rate Frequency Zm
Ki
slow, med all
1
fast
100 Hz-1 kHz 6.25
Ω
<Zm<400 k
Ω
3
fast
all other
2
Zm = 1/2
π
fC = impedance of device
Kv Table
Vout (V rms)
Kv
1.0 - 0.55
1 / Vout
0.5 - 0.3
0.5 / Vout
0.25 - 0.15
0.25 / Vout
0.10
0.11/Vout
Note that Kv equals one for the primary drive
voltages (1.0, 0.5 and 0.25 Vrms).
Kh & Kl Table
Frequency
Kl
Kh
100,120 Hz
(2 pF / Cm)
(Cm / 1600 mF)
1 kHz
(0.1 pF / Cm)
(Cm / 160 mF)
10 kHz
(0.01 pF / Cm) (Cm / 16 mF)
100 kHz
(0.02 pF / Cm) (Cm / 200
µ
F)
Cm = the capacitance of the device being
measured.
Note that Kl is negligible for capacitances less than
1590/f
µ
F and Kh is negligible for capacitances
above 159/f
µ
F, where f is the output frequency.
