
PDS_6xxx_010 71M6xxx Data Sheet
v1.2 © 2008–2011 Teridian Semiconduct or Cor por ation 5
The 71M6xxx isolated sensors prov ide a continuous data stream of ADC data plus an independent dat a
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 regi ster s.
Basic settings and functions of the 71M6xxx can be controlled by various I/O RAM registers in the
71M654x. The comm and sent towards the 71M6xxx is plac ed in t he RCMD[4:2] register of t he 71M654x,
with further specification contained in the TMUXRn[2:0] register. Refer to the 71M654x data sheets for
details.
Table 1 shows the all owabl e combinat ions of v alues in RCMD[4:2] and TMUXRn[2:0] , and the achiev ed
operation al ong with t he type and format of data sent bac k by the 71M6xxx isolated sensors.
Table 1: Remo t e Interface Commands
RCMD[4:2] TMUXRn[2:0]
R6K_RD [15:0]
Chip-characteristic
temper ature 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)
Out put of the temperature sensor, bit s [10:0]
Suppl y v oltage measurem ent , 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 d et a ils ).
The rem ote i nterfac e commands li sted in Table 1 enabl e the 71M 654x t o gather the f oll owing i nform ation
from the 71M6 xxx:
• Output of the temperature sensor
• Information on how the device is characteri z ed ov er tem per ature
• Supply voltage
• Chip version c ode
The control commands listed in Table 1 enable the 71M654x to initiate the following actions in the
71M6xxx:
• Read the 71M6xx x temperature sensor
• Read the 71M6xx x V CC sensor
• Hardware reset
With hardwar e and temperature characterization informat ion 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
coeffici ent of the 71M 6xxx V REF and the cor r espondi ng shunt resistor.
3 APPLICATIONS INFORMATION
3.1 Product Selection
A l ow-noi se dif f erenti al-input pr eam plif i er appli es gain to t he signal f rom the cur rent sen sor to the opt im al
input range of the ADC. T he c ur r ent sensor is connected to the inputs of the pream plifier through INP and
INN. The output of the pr eam plif i er connect s direc tly t o the input of the A DC. See 5 Ordering Information
for available part types. Shunt resistances from 736µΩ to as low as 50µΩ can be accommodated,
depending on desi r ed c ur r ent range and part type.