71m6521fe Maxim Integrated Products, Inc., 71m6521fe Datasheet - Page 84

• Manufacturer Part Number: 71m6521fe
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

GAIN_ADJ is a scaling factor for measurements based on the temperature. GAIN_ADJ is controlled by the MPU for
temperature compensation.
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:
where F
Page: 84 of 101
Address
Address
0x0E
0x0F
0x11
0x7C
0x7B
0x12
0x14
CE
CE
S
RATE
= sampling frequency (2520.6Hz), X = Pulse speed factor
=
TEMP_RAW_X
MAINEDGE_X
WRATE
APULSEW
GAIN_ADJ
APULSER
SAG_THR
WRATE
Name
Name
⋅
WSUM
2
46
⋅
F
Default
Default
443000
16384
S
© 2005-2008 TERIDIAN Semiconductor Corporation
N/A
N/A
122
⋅
0
0
X
Hz
,
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
Description
Kh = VMAX*IMAX*47.1132 / (In_8*WRATE*N
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).
The maximum value for WRATE is 2
Watt pulse generator input (see DIO_PW bit). The output pulse rate is:
APULSEW * F
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:
APULSER * F
loaded during a computation interval. The change will take effect at the
beginning of the next interval.
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.
Pulse Generation
S
S
*2
* 2
-32
-32
* WRATE * X * 2
71M6521DE/71M6521FE
* WRATE * X * 2
-14
15
-14
. This input is buffered and can be
– 1.
Energy Meter IC
. This input is buffered and can be
ACC
*X) Wh/pulse. The default
DATASHEET
-7
V (peak).
JANUARY 2008
v1.0