Analog Input Signal Connections - National Instruments NI 4472 User Manual

Analog Input Signal Connections

24 V Compliant
ICP Current
Source
4 mA
Common-Mode
Choke
CH0
0.01 µF
50 Ω
© National Instruments Corporation
is protected to ±42.4 V, whether power is on or off. The shield side of the
analog input channels has no overvoltage protection. Do not apply a signal
that varies by more than ±2.5 V from the ground of the NI 4472.
Figure 3-3 shows a diagram of one of the eight identical NI 4472 analog
input stages.
ICP
On/Off
0.047 µF
Calibration
Multiplexer
0.01 µF
The analog input stage presents high input impedance to the analog input
signals connected to your NI 4472. Signals are routed to the positive inputs
of the analog input stage, and their returns are routed to AIGND through a
common-mode choke. Your NI 4472 ADCs measure these signals when
they perform A/D conversions.
These input channels have 24-bit resolution and are simultaneously
sampled at software-programmable rates from 102.4 kS/s down to 1.0 kS/s
in 190.7 µS/s increments for f
Chapter 3 Device Overview and Theory of Operation
DC/AC
Coupling
Differential
Buffer
+
1 MΩ –
Gain = –12.77 dB
Figure 3-3. Analog Input Stage
> 51.2 kS/s or 95.37 µS/s increments for
s
3-3
Analog-
Lowpass
Filter
A/D
Converter
NI 4472 User Manual