71M6533 Datasheet, PDF (103/132 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS_6533_6534_004
71M6533/G/H and 71M6534/H Data Sheet
The maximum pulse rate is 3*F_S = 7.5 kHz.
Control is transferred to the MPU for pulse generation if EXT_PULSE = 1. In this case, the pulse rate is
determined by APULSEW and APULSER. The MPU loads the source for pulse generation in APULSEW
and APULSER to generate pulses. Irrespective of the EXT_PULSE status, the output pulse rate controlled
by APULSEW and APULSER is implemented by the CE only. By setting EXT_PULSE = 1, the MPU is providing
the source for pulse generation. If EXT_PULSE is 1, W0SUM_X and VAR0SUM_X are the default pulse
generation sources. In this case, creep cannot be controlled since it is an MPU function.
PULSE_WIDTH allows adjustment of the pulse width for compatibility with calibration and other external
equipment. The minimum pulse width possible is 66.16µs.
The maximum time jitter is1/6 of the MUX cycle period (nominally 67 µs) and is independent of the number
of pulses measured. Thus, if the pulse generator is monitored for one 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 (as defined in the CECONFIG register
with the PULSE_FAST and PULSE_SLOW bits).
Table 64: CE Pulse Generation Parameters
CE
Address
0x21
0x22
0x23
0x41
0x38
0x42
0x43
0x44
0x45
0x46
0x47
0x48
Name
WRATE
KVAR
SUM_PRE
APULSEW
PULSEWIDTH
APULSER
APULSEX
APULSEY
WSUM_ACCUM
VSUM_ACCUM
SUM2_ACCUM
SUM3_ACCUM
Default
171
6448
2520
0
12
0
0
0
0
0
0
0
Description
Kh = VMAX*IMAX*66.1782 / (In_8*WRATE*N_ACC*X) Wh/pulse.
Scale factor for VAR measurement.
PRE_SAMPS * SUM_CYCLES (N_ACC)
Wh pulse (WPULSE) generator input to be updated by the MPU
when using external pulse generation. The output pulse rate is:
APULSEW * F_S * 2^-32 * WRATE * X * 2^-14.
This input is buffered and can be updated by the MPU during a
conversion interval. The change will take effect at the beginning
of the next interval.
Register for pulse width control of XPULSE and YPULSE. The
maximum pulse width is (2*PULSEWIDTH+1)*(1/FS). The default
value will generate pulses of 10 ms width at FS = 2520.62 Hz.
VARh (RPULSE) pulse generator input.
Pulse generator input for XPULSE output.
Pulse generator input for YPULSE output.
Roll-over accumulator for WPULSE. A pulse is generated when
this register reaches 2³¹.
Roll-over accumulator for RPULSE. A pulse is generated when
this register reaches 2³¹.
Roll-over accumulator for the XPULSE pulse output.
Roll-over accumulator for the YPULSE pulse output.
Rev 2
103