71M6xxx Data Sheet
5
The 71M6xxx isolated sensors provide a continuous data stream of ADC data plus an independent data
stream that contains auxiliary information as requested by the 71M654x. The ADC data is processed by
CE code in the 71M654x and stored in CE RAM. Auxiliary information is processed by the MPU of the
71M654x using I/O RAM registers.
Basic settings and functions of the 71M6xxx can be controlled by various I/O RAM registers in the
71M654x. The command sent towards the 71M6xxx is placed in the RCMD[4:2] register of the 71M654x,
with further specification contained in the TMUXRn[2:0] register. Refer to the 71M654x data sheets for
details.
Table 1 shows the allowable combinations of values in RCMD[4:2] and TMUXRn[2:0] , and the achieved
operation along with the type and format of data sent back by the 71M6xxx isolated sensors.
Table 1: Remote Interface Commands
RCMD[4:2] TMUXRn[2:0]
R6K_RD [15:0]
Chip-characteristic
temperature data
TRIMT (see note), use bits [8:1]
TRIMBGC (see note), use bits [15:6]
TRIMBGA (see note), use bits [15:8]
001 11X
TRIMBGB bits [15:8], TRIMBGD bits [7:0]
(see note)
Output of the temperature sensor, bits [10:0]
Supply voltage measurement , bits [7:0]
Chip version code, use bits [15:8]
Note: TRIMBGA to TRIMBGD and TRIMT are values used for characterizing the individual 71M6xxx over temperature. Availability
of TRIMBGA to TRIMBGD and TRIMT depends on the part number (see Table 10 for details)
.
The remote interface commands listed in Table 1 enable the 71M654x to gather the following information
from the 71M6xxx:
• Output of the temperature sensor
• Information on how the device is characterized over temperature
• Supply voltage
• Chip version code
The control commands listed in Table 1 enable the 71M654x to initiate the following actions in the
71M6xxx:
• Read the 71M6xxx temperature sensor
• Read the 71M6xxx VCC sensor
• Hardware reset
With hardware and temperature characterization information on each connected 71M6xxx isolated sensor
available to the 71M654x host MPU, temperature compensation of the energy measurement can be
implemented based on the individual temperature characteristics of the 71M6xxx isolated sensors. For
example, when the 71M6xxx are used in a polyphase meter containing three shunt resistors, the
temperature increase in each 71M6xxx can be monitored and used to compensate for the temperature
coefficient of the 71M6xxx VREF and the corresponding shunt resistor.
3 APPLICATIONS INFORMATION
3.1 Product Selection
A low-noise differential-input preamplifier applies gain to the signal from the current sensor to the optimal
input range of the ADC. The current sensor is connected to the inputs of the preamplifier through INP and
INN. The output of the preamplifier connects directly to the input of the ADC. See 5 Ordering Information
for available part types. Shunt resistances from 736µΩ to as low as 50µΩ can be accommodated,
depending on desired current range and part type.
