Manual
71M6541 Demo Board REV 3.0 User’s Manual
31 Rev 4.0
Table 1-9: IMAX for Various Shunt Resistance Values and Remote Sensor Types
Remote
Sensor
Interface
Rated
Current
[A]
Max. Voltage
at IAP/IAN
[mV]
Shunt
Resistor
Value [µΩ]
IMAX
[A]
IMAX
En-
try at MPU
0x03
WRATE
for
kH = 1.0 and
VMAX = 600 V
CE ad-
dress
0x30
71M6601 60 62.5
500
88.39
+884
383
2483
400
110.49
+1105
497
2483
300
147.31
+1473
638
2483
250
176.78
+1768
766
2483
200
220.97
+2209
957
2483
160
276.21
+2762
1196
2483
120
368.28
+3683
1595
2483
71M6201 200 17.86
75
168.4
+1684
729
8691
50
252.6
+2526
1094
8691
25
505.1
+5051
2188
8691
The meter constant kh (Wh per pulse) is calculated as follows:
Kh = 109.1587*
VMAX*IMAX / (SUM_SAMPS*WRATE*X),
where
VMAX = RMS voltage at the meter input corresponding to 176.8 mV RMS at the VA pin of the
71M6541. This value is determines by the divider ratio of the voltage-divider resistors. For the
71M6541 Demo Board, this value is 600.
IMAX = RMS current through one current sensor corresponding to 176.8 mV RMS at the IAP/IAN or
IBP/IBN pins of the 71M6541, as determined by the formula above.
Note: For the IBP/IBN pins, no physical analog voltage exists due to the digital nature of the cur-
rent measurement via the remote interface.
SUM_SAMPS = The value in the SUM_SAMPS register in I/O RAM (2520 for this version of the Demo
Code).
WRATE = The value in the pulse rate adjustment register of the CE.
X = The pulse rate adjustment modifier, determined by the
PULSE_FAST and PULSE_SLOW bits in
the
CECONFIG register.
A kh of 1 (1.00 Wh per pulse) is achieved by the following combination of system settings:
VMAX = 600 V
IMAX = 368.3 A, based on R
S
= 120 μΩ
SUM_SAMPS = 2520
WRATE = 1595, based on X = 6, and PULSE_FAST = 0 and PULSE_SLOW = 0
1.10.5 DETERMINING THE TYPE OF 71M6X0X
Sometimes it is useful to be able to determine the type of 71M6X0X Remote Sensor Interface that is mounted
on the Demo Board. The CLI can be used to find out which 71M6X0X Remote Sensor Interface is present, us-
ing the following steps:
1) Type 6R1.14 at the command prompt (>).
2) The CLI will respond with a two-byte hex value, e.g., E9DB.
3) Write the hex value out as binary sequence, e.g., 1110 1001 1101 1011. Bits 4 and 5 determine the
type of the 71M6X0X Remote Sensor Interface, as shown in Table 1-10.