User`s manual

XP850022 s I/O Configurations
(
–
+
CH0–CH3
VREF+
A/D
converter
+5ANA
10 kΩ
10 kΩ
U3
U2
VREF+
+5ANA
RP2
+5ANA
0.01 µF
RP3
RP4
RP3
RP4
R
g
R bias
VRn-
VRn+
AIN0AIN3
How to Set Up An XP8500
Conditioned Inputs (CH0CH3)
Signals from devices connected to a conditioned input channel on H1 go to
an inverting input on one of the four op-amps in U2, as shown in Fig-
ure3-3. User-selectable precision resistors R1 through R8 (R
g
and R
bias
)
set the gain and bias voltages of the op-amps to match the voltage range of
the input to the fixed 2.5 V range of the A/D converter chip.
Figure 3-3. Schematic of XP8500 Signal Conditioning
The 10 kΩ input resistors, RP3 or RP4, are fixed; 0.01 µF feedback
capacitors roll off the high-frequency response of the op-amps to attenuate
noise. Equation (3-1) gives the 3 dB corner frequency.
For the factory default, where the gain is 0.25 using R
g
= 2370 Ω, the 3dB
corner frequency is 6715 Hz.
Strip sockets accommodate resistors R1R8, as shown in Figure 3-4. The
factory-installed gain resitors and bias resistors are 2370Ω and 39.2 kΩ,
respectively, and provide a range of 0 V to 10V for the inputs to be
conditioned.
Z-World offers the XP8500 with customer-specified surface-
mounted gain and bias resistors installed at R1R8. For
ordering information, call your Z-World Sales Representative
at [phone].
F01.0R2
1
f
g
3db
µπ ××
=
(3-1)