78M6612 Datasheet, PDF (87/111 Pages) Teridian Semiconductor Corporation – Single-Phase, Dual-Outlet Power and Energy Measurement IC

DS_6612_001
78M6612 Data Sheet
4.4.7.3 Other Measurement Parameters
MAINEDGE_X is useful for implementing a real-time clock based on the input AC signal. MAINEDGE_X is
the number of half-cycles accounted for in the last accumulated interval for the AC signal.
TEMP_RAW may be used by the MPU to monitor chip temperature or to implement temperature
compensation.
CE
Address
0x73
0x71
0x19
0x11
Name
MAINEDGE_X
TEMP_RAW_X
GAIN_ADJ
SAG_THR
Default Description
N/A
N/A
16384
313000
The number of zero crossings of the selected voltage in
the previous accumulation 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.
4.4.7.4 Pulse Generation
CE
Address
Name
0x0F
WRATE
Default Description
Kh = VMAX *IMAX * 47.1132 / (WRATE * N_ACC * X)
Wh/pulse. The default value results in a Kh of 3.2 Wh/pulse
486 ^{when 2520 samples are taken in each accumulation interval}
(and VMAX=600, IMAX = 52, X = 6).
The maximum value for WRATE is 2¹⁵ – 1.
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 measurement 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 measurement unit of 120 V and 30 A results in one pulse per second. If the load is
240 V at 150 A, ten pulses per second will be generated.
The maximum pulse rate is 7.5 kHz.
The maximum time jitter is 67 µs and is independent of the number of pulses measured. Thus, if the
pulse generator is monitored for 1 second, the peak jitter is 67 ppm. After 10 seconds, the peak jitter is
6.7 ppm.
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 (2520.6 Hz), X = Pulse speed factor.
Rev. 1.2
87