JYTEK USB-62405, User Manual

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28 Operation
3.2 Analog Input
3.2.1 Analog Input Front End Configuration
Figure 3-2: USB-62405 Analog Front End
Input Configuration: Differential/Pseudo-Differential
Differential input mode provides anode and cathode inputs of the BNC
connector that respond to signal voltage differences therebetween. If
the signal source is ground-referenced, the differential input mode can
be used for common-mode noise rejection.
If the signal source is a floating signal, setting pseudo-differential input
mode will provide a reference ground connected to the cathode input of
the BNC through a 20 kΩ resistor.
Recommended configurations for the signal sources are as follows.
Table 3-1: Signal Source-Card Configuration
Input Coupling
When DC coupling is selected, DC offset present in the input signal is
passed to ADC. DC coupling configuration is indicated when the signal
source has a small offset voltage or if the DC content of the signal is
important. When AC coupling is selected, DC offset present in the input
signal is removed. AC coupling configuration is indicated when the DC
Signal Source Card Configuration
Floating Pseudo-differential
Ground-reference Differential
Calibration
Circuit
24 Bit ADC
AI
IEPE
Circuit
AC
Coupling
circuit
Diff input
ADC Driver
Differential/
Psuedo-
differential
Switch
Circuit