71M6541D Datasheet, PDF (23/166 Pages) Maxim Integrated Products – 0.1% Accuracy Over 2000:1 Current Range Energy Meter ICs

71M6541D/F/G and 71M6542F/G Data Sheet
111
Reserved
Notes:
1. Only two codes of RCMD[4:2] (SFR 0xFC[4:2]) are relevant for normal
operation. These are RCMD[4:2] = 001 and 010. Codes 000 and 101
are invalid and will be ignored if used. The remaining codes are
reserved and must not be used.
2. For the RCMD[1:0] control field, codes 01, 10 and 11 are valid and 00
is invalid and must not be used.
Table 6 shows the allowable combinations of values in RCMD[4:2] and TMUXRn[2:0], and the
corresponding data type and format sent back by the 71M6x01 isolated sensor and how the data is stored
in RMT_RD[15:8] and RMT_RD[7:0]. The MPU selects which of the three phases is read by asserting the
proper code in the RCMD[1:0] field, as shown in Table 5.
Table 6: Remote Interface Read Commands
RCMD[4:2] TMUXRn[2:0]
Read Operation
RMT_RD [15:8]
RMT_RD [7:0]
001
010
010
010
Notes:
1.
2.
3.
00X
TRIMT[7:0]
(trim fuse for all 71M6x01)
TRIMT[7]=RMT_RD[8]
TRIMT[6:0]=RMT_RD[7:1]
00X
STEMP[10:0]
(sensed 71M6x01 temperature)
STEMP[10:8]=RMT_RD[10:8]
(RMT_RD[15:11] are sign extended)
STEMP[7:0]
01X
VSENSE[7:0]
(sensed 71M6x01 supply voltage)
All zeros
VSENSE[7:0]
10X
VERSION[7:0]
(chip version)
VERSION[7:0]
All zeros
TRIMT[7:0] is the VREF trim value for all 71M6x01 devices. Note that the TRIMT[7:0] 8-bit value is formed
by RMT_RD[8] and RMT_RD[7:1]. See the 71M6xxx Data sheet for more information on TRIMT[7:0]
See the 71M6xxx Data Sheet for the equation to calculate temperature from the STEMP[7:0] value read from
the 71M6x01.
See the 71M6xxx Data Sheet for the equation to calculate temperature from the VSENSE[7:0] value read from
the 71M6x01.
With hardware and trim-related information on each connected 71M6x01 Isolated Sensor available to the
71M6541D/F/G, the MPU can implement temperature compensation of the energy measurement based on
the individual temperature characteristics of the 71M6x01 Isolated Sensor. See 4.7 Metrology
Temperature Compensation on page 97 for details.
Table 7 shows all I/O RAM registers used for control of the external 71M6x01 Isolated Sensors. See the
71M6xxx Data Sheet for additional details.
Name
RCMD[4:0]
PERR_RD
PERR_WR
CHOPR[1:0]
Table 7: I/O RAM Control Bits for Isolated Sensor
Address
SFR
FC[4:0]
RST WAKE
Default Default
0
0
R/W Description
When the MPU writes a non-zero value to RCMD,
the 71M654x issues a command to the cor-
R/W
responding isolated sensor selected with
RCMD[1:0]. When the command is complete, the
71M654x clears RCMD[4:2]. The command code
itself is in RCMD[4:2].
SFR FC[6]
SFR FC[5]
0
The 71M654x sets these bits to indicate that a
0
R/W
parity error on the isolated sensor has been de-
tected. Once set, the bits are remembered until
they are cleared by the MPU.
2709[7:6] 00
The CHOP settings for the isolated sensors.
00 – Auto chop. Change every multiplexer frame.
00 R/W 01 – Positive
10 – Negative
11 – Same as 00