Allen-Bradley 1756-IR12 - Page 54

54 Rockwell Automation Publication 1756-UM540E-EN-P - December 2017
Chapter 3 1756-IF8I Isolated Analog Input Module
Figure 6 - 1756-IF8I Module Field-side Circuit with Voltage Input
Figure 7 - 1756-IF8I Input Module Field-side Circuit with an Externally-powered Current
Input Loop
RTN-x
1 µA
Pullup
0.1 µF
IN_x/V
A/D Converter
7500 Ω
2.5V Vref
+
IN_x/I/SRC
1000 Ω
55 Ω
0.01 µF0.01 µF
–
1000 Ω
20 Ω
Voltage
Source
0.01 µF
0.01 µF
PGA
RTN-x
0.1 µF
IN_x/V
A/D Converter
7500 Ω
IN_x/I/SRC
1000 Ω
55 Ω
4…20 mA
Trans mitter
0.01 µF0.01 µF
1000 Ω
20 Ω
Transm it te r
Power
0.01 µF
0.01 µF
Current Limit
24.9 Ω
25 Ω
i_sense
2.5V Vref
PGA
+
–
+
–