71M6521DE/71M6521FE
Energy Meter IC
DATASHEET
JANUARY 2008
CE
Address
Name
Default
Description
The number of zero crossings of the selected voltage in the previous ac-
cumulation interval. Zero crossings are either direction and are debounced.
0x7C
MAINEDGE_X
N/A
0x7B
0x12
TEMP_RAW_X
GAIN_ADJ
N/A
Filtered, unscaled reading from the temperature sensor.
16384
Scales all voltage and current inputs. 16384 provides unity gain.
The threshold for sag warnings. The default value is equivalent to 80V RMS
if VMAX = 600V. The LSB value is VMAX * 4.255*10-7V (peak).
0x14
SAG_THR
443000
GAIN_ADJ is a scaling factor for measurements based on the temperature. GAIN_ADJ is controlled by the MPU for
temperature compensation.
Pulse Generation
CE
Address
Name
Default
Description
Kh = VMAX*IMAX*47.1132 / (In_8*WRATE*NACC*X) Wh/pulse. The default
value results in a Kh of 3.2Wh/pulse when 2520 samples are taken in each
accumulation interval (and VMAX=600, IMAX = 208, In_8 = 1, X = 6).
0x11
WRATE
122
The maximum value for WRATE is 215 – 1.
Watt pulse generator input (see DIO_PW bit). The output pulse rate is:
APULSEW * FS * 2-32 * WRATE * X * 2-14. This input is buffered and can be
loaded during a computation interval. The change will take effect at the
beginning of the next interval.
0x0E
0x0F
APULSEW
APULSER
0
0
VAR pulse generator input (see DIO_PV bit). The output pulse rate is:
APULSER * FS*2-32 * WRATE * X * 2-14. This input is buffered and can be
loaded during a computation interval. The change will take effect at the
beginning of the next interval.
WRATE controls the number of pulses that are generated per measured Wh and VARh quantities. The lower WRATE is the
slower the pulse rate for measured energy quantity. The metering constant Kh is derived from WRATE as the amount of energy
measured for each pulse. That is, if Kh = 1Wh/pulse, a power applied to the meter of 120V and 30A results in one pulse per
second. If the load is 240V at 150A, ten pulses per second will be generated.
The maximum pulse rate is 7.5kHz.
The maximum time jitter is 67µs and is independent of the number of pulses measured. Thus, if the pulse generator is
monitored for 1 second, the peak jitter is 67ppm. After 10 seconds, the peak jitter is 6.7ppm.
The average jitter is always zero. If it is attempted to drive either pulse generator faster than its maximum rate, it will simply
output at its maximum rate without exhibiting any rollover characteristics. The actual pulse rate, using WSUM as an example,
is:
WRATE ⋅WSUM ⋅ FS ⋅ X
,
RATE =
Hz
246
where FS = sampling frequency (2520.6Hz), X = Pulse speed factor
Page: 84 of 101
© 2005-2008 TERIDIAN Semiconductor Corporation
v1.0
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
