71M6521BE Datasheet, PDF (79/97 Pages) Teridian Semiconductor Corporation – Energy Meter IC

71M6521BE
Energy Meter IC
DATA SHEET
JANUARY 2008
CE TRANSFER VARIABLES
When the MPU receives the XFER_BUSY interrupt, it knows that fresh data is available in the transfer variables.
Fundamental Energy Measurement Variables
The table below describes each transfer variable for fundamental energy 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
0x11D8
0x11C8
Name
W0SUM_X
W1SUM_X
Description
The sum of Watt samples from each wattmeter element (In_8 is the gain
configured by IA_SHUNT or IB_SHUNT).
LSB = 6.6952*10^-13 VMAX IMAX / In_8 Wh.
WxSUM_X is the Wh value accumulated for element ‘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 0.08356 µWh.
Instantaneous Energy Measurement Variables
The Frequency measurement is computed using the Frequency locked loop 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.
CE
Address
0x11E4
0x11F0
0x11DC
0x11CC
0x11E0
0x11D0
0x11F4
0x11D4
0x11C4
Name
FREQ_X
MAINEDGE_X
I0SQSUM_X
I1SQSUM_X
V0SQSUM_X
V1SQSUM_X
WSUM_ACCUM
I0SQRT_X
I1SQRT_X
Description
Fundamental frequency. LSB
≡ ^FS
2 ³²
≈ 0.587 ⋅10^−6 Hz
The number of zero crossings of the selected voltage in the previous ac-
cumulation interval. Zero crossings are either direction and are de-
bounced.
The sum of squared current samples from each element.
LSB = 6.6952*10^-13 IMAX² / In_8² A²h
The sum of squared voltage samples from each element.
LSB= 6.6952*10^-13 VMAX² V²h
Rollover accumulator for WPULSE.
RMS current determined by calculating the square root of I0SQSUM_X
and I1SQSUM_X
V1.0
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