71M6543F/H and 71M6543G/GH Data Sheet
Using settings for the I/O RAM Mnemonics listed in Table 1 and Table 2 that do not match
those required by the corresponding CE code being used may result in undesirable side
effects and must not be selected by the MPU. Consult your local Teridian representative to
obtain the correct CE code and AFE / MUX settings corresponding to the application.
For a polyphase configuration with neutral current sensing using shunt resistor current sensors and the
71M6xx3 isolated sensors, as shown in Figure 2, the IADC0-IADC1 input must be configured as a
differential input, to be connected to a local shunt (see Figure 30 for the shunt connection details). The
local shunt connected to the IADC0-IADC1 input is used to sense the Neutral current. The voltage
sensors (VADC8, VADC9 and VADC10) are also directly connected to the 71M6543 (see Figure 27 for
the connection details) and are also routed though the multiplexer, as seen in Figure 2. Meanwhile, the
IADC2-IADC3, IADC4-IADC5 and IADC6-IADC7 current inputs are configured as remote sensor digital
interfaces and the corresponding samples are not routed through the multiplexer. For this configuration,
the multiplexer sequence is as shown in Figure 4.
For a polyphase configuration with optional neutral current sensing using Current Transformer (CTs)
sensors, as shown in Figure 3, all four current sensor inputs must be configured as a differential inputs, to
be connected to their corresponding CTs (see Figure 29 for the differential CT connection details). The
IADC0-IADC1 current sensor input is optionally used to sense the Neutral current for anti-tampering
purposes. The voltage sensors (VADC8, VADC9 and VADC10) are directly connected to the 71M6543
(see Figure 27 for the voltage sensor connection details). No 71M6xx3 isolated sensors are used in this
configuration and all sensors are routed though the multiplexer, as seen in Figure 3. For this
configuration, the multiplexer sequence is as shown in Figure 5.
The multiplexer sequence shown in Figure 4 corresponds to the configuration shown in Figure 2. The
frame duration is 13 CK32 cycles (where CK32 = 32,768 Hz), therefore, the resulting sample rate is
32,768 Hz / 13 = 2,520.6 Hz. Note that Figure 4 only shows the currents that pass through the 71M6543
multiplexer, and does not show the currents that are copied directly into CE RAM from the remote
sensors (see Figure 2), which are sampled during the second half of the multiplexer frame. The two
unused conversion slots shown are necessary to produce the desired 2,520.6 Hz sample rate.
Multiplexer Frame
Settle
MUX_DIV[3:0] = 6 Conversions
CK32
MUX STATE
S
0
IN
1
2
3
VA
4
VB
5
VC
S
Unused
Unused
CROSS
MUX_SYNC
Figure 4: States in a Multiplexer Frame (MUX_DIV[3:0] = 6)
The multiplexer sequence shown in Figure 5 corresponds to the CT configuration shown in Figure 3.
Since in this case all current sensors are locally connected to the 71M6543, all currents are routed
through the multiplexer, as seen in Figure 3. For this multiplexer sequence, the frame duration is 15 CK32
cycles (where CK32 = 32,768 Hz), therefore, the resulting sample rate is 32,768 Hz / 15 = 2,184.5 Hz.
Multiplexer Frame
Settle
MUX_DIV[3:0] = 7 Conversions
CK32
MUX STATE
S
0
1
2
3
4
5
6
S
IB
VB
IC
VC
IN
IA
VA
CROSS
MUX_SYNC
Figure 5: States in a Multiplexer Frame (MUX_DIV[3:0] = 7)
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