Slew rate limit of the internal op amp is approximately
3V/µs. For most applications, the slew rate of VOUT should
be limited to 1V/µs or less. The rate of change is propor-
0
–10
–20
–30
–40
–50
tional to IIN and inversely proportional to CINT
:
–20dB/decade
slope
Corner at
f = 0.32/TINT
IIN
Slew Rate =
CINT
–3dB at
f = 0.44/TINT
This can be important in some applications since the slew-
induced input voltage is applied to the sensor or signal
source. The slew-induced input voltage can be reduced by
increasing CINT, which reduces the output slew rate.
● ● ●
1/10TINT
1/TINT
Frequency
10/TINT
NONLINEARITY
Careful nonlinearity measurements of the IVC102 yield
typical results of approximately ±0.005% using the internal
input capacitors (CINT = 100pF). Nonlinearity will be de-
graded by using an external integrator capacitor with poor
voltage coefficient. Performance with the internal capacitors
is typically equal or better than the sensors it is used to
measure. Actual application circuits with sensors such as a
photodiode may have other sources of nonlinearity.
FIGURE 5. Frequency Response of Integrating Converter.
The input resistance seen at pin 2 includes an additional
1.5kΩ, the on-resistance of S1. The total input resistance is
the sum of the switch resistance and RIN, or 2.5kΩ in this
example.
®
10
IVC102
BB [ BURR-BROWN CORPORATION ]
