71M6521DE Datasheet, PDF (87/107 Pages) Teridian Semiconductor Corporation – Energy Meter IC

71M6521DE/DH/FE Data Sheet
CE
Address
0x7C
0x7B
0x12
0x14
Name
MAINEDGE_X
TEMP_RAW_X
GAIN_ADJ
SAG_THR
Default
N/A
N/A
16384
443000
Description
The number of zero crossings of the selected voltage in the previous ac-
cumulation interval. Zero crossings are either direction and are debounced.
Filtered, unscaled reading from the temperature sensor.
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).
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
0x11
0x0E
0x0F
Name
WRATE
APULSEW
APULSER
Default Description
Kh = VMAX*IMAX*47.1132 / (In_8*WRATE*N_ACC*X) Wh/pulse. The default
value results in a Kh of 3.2Wh/pulse when 2520 samples are taken in each
122
accumulation interval (and VMAX=600, IMAX = 208, In_8 = 1, X = 6).
The maximum value for WRATE is 2¹⁵ – 1.
Watt pulse generator input (see DIO_PW bit). The output pulse rate is:
0
APULSEW * F_S * 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.
VAR pulse generator input (see DIO_PV bit). The output pulse rate is:
0
APULSER * F_S*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:
RATE
=
WRATE ⋅WSUM
2 ⁴⁶
⋅ F_S
⋅
X
Hz ^,
where F_S = sampling frequency (2520.6Hz), X = Pulse speed factor
Rev 2
Page: 87 of 107