71M6531D_10 Datasheet, PDF (63/120 Pages) Teridian Semiconductor Corporation – Energy Meter IC

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 * R_out/(R_out + R_in)
VA
V_in
R_in
R_out
Figure 28: Resistive Voltage Divider
I_in
I_out
R
1/N
Filter
IA
V_out
I_IN
I_OUT
V3P3
1/N
V_OUT
R
V_DIFF
InP
V3P3A
InN
Figure 29: CT with Single Ended (Left) and Differential Input (Right) Connection
I_in
IA
I_{in 1/N}
Vout = c*dI_in /dt
IAP
R
V_out
V_out
V3P3A
V3P3
Figure 30: Resistive Shunt (Left) and Rogowski Sensor (Right) Connection
IAN
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.
v1.3
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