71M6511 Datasheet, PDF (70/95 Pages) Teridian Semiconductor Corporation – Single-Phase Energy Meter IC

CE
Address
0x40
0x54
0x2E
71M6511/71M6511H
Single-Phase Energy Meter IC
DATA SHEET
AUGUST 2007
Name
TEMP_X
TEMP_RAW_X
GAIN_ADJ
Description
Deviation from Calibration temperature. LSB = 0.1 ⁰C.
Filtered, unscaled reading from temperature sensor. This value should be
written to TEMP_NOM during meter calibration.
Scales all voltage and current inputs. 16384 provides unity gain. Default is
16384. If EXT_TMP = 0, GAIN_ADJ is updated by the CE.
Pulse Generation
Input variables: The combination of the PULSE_SLOW and PULSE_FAST parameters control the speed of the pulse rate.
The default values of 1 and 1 will maintain the original pulse rate given by the Kh equation.
WRATE controls the number of pulses that are generated per measured Wh and VARh quantities. The lower WRATE it is the
slower is the pulse rate for measured power 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.
Control is transferred to the MPU for pulse generation if EXT_PULSE > 0. In this case, the pulse rate is determined by
APULSEW and APULSER. The MPU has to load 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 > 0, the MPU is providing the source for pulse generation. If EXT_PULSE is negative,
W0SUM_X and VAR0SUM_X are the default pulse generation sources. In this case, creep cannot be controlled since it is an
MPU function.
The maximum pulse rate is F_S /2= 1260.3Hz (MUX_DIV = 1).
PULSE_WIDTH allows adjustment of the pulse width for compatibility with calibration and other external equipment. When
MUX_DIV = 1, the minimum pulse width possible is 397µs.
The maximum time jitter is 397µs (for MUX_DIV = 1) and is independent of the number of pulses measured. Thus, if the pulse
generator is monitored for 1 second, the peak jitter is 397PPM. After 10 seconds, the peak jitter is 39.7PPM. 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 roll-over characteristics. The actual pulse rate, using WSUM as an example, is:
RATE
=
X
⋅WRATE ⋅WSUM
2 ⁴⁶
⋅ F_S
Hz
Where F_S = 2520.6Hz (sampling frequency for MUX_DIV = 1) or 3276.8Hz (sampling frequency for MUX_DIV = 2) and X is the
pulse gain factor derived from CE variables PULSE_SLOW and PULSE_FAST (see table below).
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