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
Name
Description
0x11D8
W0SUM_X
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.
0x11C8
W1SUM_X
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
Name
Description
FS
232
≈ 0.587 ⋅10−6 Hz
0x11E4
FREQ_X
Fundamental frequency. LSB ≡
The number of zero crossings of the selected voltage in the previous ac-
cumulation interval. Zero crossings are either direction and are de-
bounced.
0x11F0
MAINEDGE_X
0x11DC
0x11CC
0x11E0
0x11D0
I0SQSUM_X
I1SQSUM_X
V0SQSUM_X
V1SQSUM_X
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
0x11F4
0x11D4
0x11C4
WSUM_ACCUM
I0SQRT_X
Rollover accumulator for WPULSE.
RMS current determined by calculating the square root of I0SQSUM_X
and I1SQSUM_X
I1SQRT_X
V1.0
© 2005-2008 TERIDIAN Semiconductor Corporation
Page: 79 of 97
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
