PDS_6xxx_010
71M6xxx Data Sheet
The shunt resistance must be balanced with the maximum current range of the part type, as shown in
Table 2. Various combinations of current ranges and shunt resistance values are possible. However, the
shunt resistance for a given current has to be chosen carefully as not to exceed the maximum RMS
voltage at the INP/INN pins of the 71M6xxx. The maximum wattage of the shunt resistor is another
consideration that applies to the resistance range of the shunt.
Table 2: Product Variations
Maximum
Maximum
Shunt
Typical
Shunt
Maximum
Current
(A)
Accuracy
Class2
(%)
RMS
Voltage at
INP/INN
(mV)
Shunt
Power4
(W)
Part
Application1
Resistance3
(µΩ)
Resistance5
(µΩ)
71M6601
71M6603
71M6103
71M6113
71M6201
71M6203
S
P
1
1
60
44
736
1.44
400
1
P
100
200
19.6
12.6
196
63
1.2
2.0
120
50
0.5
0.2
0.2
S
P
Note 1: S = single phase, P = polyphase.
Note 2: Accuracy over temperature (-40°C to +85°C for 71M620x parts, -20°C to +60° for all other parts), when combined with
71M654x or 71M654xH IC.
Note 3: Maximum resistance at maximum current.
Note 4: Power at maximum current and typical shunt resistance.
Note 5: Typical resistance values provide room for overhead while maintaining optimum dynamic range.
The inputs of the preamplifier are referenced to local ground (the GND pin of the 71M6xxx). This means
that in an isolated system, the INP and INN pins have to be biased towards this local GND. See 3.2.1
Current Sensor Side for details.
3.2
External Components for the 71M6xxx
3.2.1 Current Sensor Side
Figure 2 shows the external components required for the 71M6xxx. It is recommended to use the
following components:
•
•
•
1.0µF capacitor between the GND and VCC pins. This capacitor minimizes the VCC ripple
voltage.
One 1kΩ resistor each from the sensor output pins to GND. These resistors help to bias the input
voltage at the INP and INN pins towards GND.
In environments where EMC is a concern, ferrite beads can be placed between the sense pins of
the shunt resistor and the INP/INN pins of the 71M6xxx.
3.2.2 Pulse Transformer
A low-cost pulse transformer is used for the link between the 71M654x and the 71M6xxx. It is the
responsibility of the meter system designer to qualify the transformer used in the system over the required
operating temperature range. The following commercially available transformer is suitable for this
application:
•
Würth Electronics Midcom Inc., P/N 750-11-0056 REV 2 (www.midcom-inc.com)
v1.2
© 2008–2011 Teridian Semiconductor Corporation
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