FDS 6531/6532 005
Data Sheet 71M6531D/F-71M6532D/F
3
Application Information
3.1
Connection of Sensors
Figure 28 through Figure 30 show how resistive dividers, current transformers, Rogowski coils and resistive
shunts are connected to the voltage and current inputs of the 71M6531.
The analog input pins of the 71M65XX are designed for sensors with low source impedance. RC
filters with resistance values higher than those implemented in the Teridian Demo Boards should be
avoided.
VA = Vin * Rout/(Rout + Rin)
VA
Rin
Vin
Rout
Figure 28: Resistive Voltage Divider
Iin
Iout
IIN
IOUT
IA
InP
VDIFF
VOUT
Vout
R
R
V3P3A
InN
V3P3
1/N
1/N
Filter
Figure 29: CT with Single Ended (Left) and Differential Input (Right) Connection
Iin
Iin
1/N
Vout = c*dIin /dt
IA
IAP
Vout
Vout
V3P3A
IAN
R
V3P3
Figure 30: Resistive Shunt (Left) and Rogowski Sensor (Right) Connection
3.2
Connecting 5-V Devices
All digital input pins of the 71M6531D/F and 71M6532D/F are compatible with external 5-V devices. I/O
pins configured as inputs do not require current-limiting resistors when they are connected to external 5 V
devices.
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