Datasheet

71M6513/71M6513H
3-Phase Energy Meter IC
DATA SHEET
AUGUST 2011
Page: 70 of 104 © 2005-2011 Teridian Semiconductor Corporation
A Maxim Integrated Products Brand
CE
Address
Name Default Description
0x31 SAG_THR
+23,930,000
(0x16D23AA)
Meter voltage inputs must be above this threshold to prevent sag alarms.
LSB = VMAX * 7.879810
-9
V.
For example, if a sag threshold of 80V RMS is desired,
9
108798.7
280
_
−
⋅⋅
=
VMAX
THRSAG
0x32 SAG_CNT 80
Number of consecutive voltage samples below SAG_THR before a sag alarm
is declared (80*397µs = 31.8ms).
CE Transfer Variables
When the MPU receives the XFER_BUSY interrupt, it knows that fresh data is available in the transfer variables. CE transfer
variables are modified during the CE code pass that ends with an XFER_BUSY interrupt. They remain constant throughout
each accumulation interval. In this data sheet, the names of CE transfer variables always end with _X.
Fundamental Power Measurement Variables
The table below describes each transfer variable for fundamental power measurement. All variables are signed 32 bit integers.
Accumulated variables such as WSUM are internally scaled so they have at least 2x margin before overflow when the
integration time is 1 second. Additionally, the hardware will not permit output values to ‘fold back’ upon overflow.
CE
Address
Name Description
0x42
WSUM_X
The signed sum: W0SUM_X+W1SUM_X+W2SUM_X
0x43
W0SUM_X
The sum of Watt samples from each wattmeter element.
LSB = 9.4045*10
-13
VMAX IMAX / In_8 Wh.
0x44 W1SUM_X
0x45 W2SUM_X
0x46 VARSUM_X
The signed sum: VAR0SUM_X+VAR1SUM_X+VAR2SUM_X
0x47 VAR0SUM_X
The sum of VAR samples from each wattmeter element.
LSB = 9.4045*10
-13
VMAX IMAX / In_8 VARh.
0x48 VAR1SUM_X
0x49 VAR2SUM_X
WSUM_X and VARSUM_X are the signed sum of Phase-A, Phase-B and Phase-C Wh or VARh values according to the
metering equation specified in the I/O RAM register EQU. WxSUM_X is the Wh value accumulated for phase ‘x’ in the last
accumulation interval and can be computed based on the specified LSB value.
For example, with VMAX = 600V and IMAX = 208A, LSB (for WxSUM_X ) is 0.1173 µWh.
Instantaneous Power Measurement Variables
The FREQSEL Register selects the input phase used for frequency measurement and for the MAIN_EDGE counter. The
frequency measurement is implemented using the frequency locked loop of the CE for the selected phase.
IxSQSUM_X and VxSQSUM are the squared current and voltage samples acquired during the last accumulation interval.
INSQSUM_X can be used for computing the neutral current.