71m6521be Maxim Integrated Products, Inc., 71m6521be Datasheet - Page 81

• Manufacturer Part Number: 71m6521be
• Description: Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

WRATE controls the number of pulses that are generated per measured Wh 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. X is controlled by the PULSE_FAST and PULSE_SLOW bits
in the CECONFIG register.
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
The table below lists the parameters that are typically entered to effect calibration of meter accuracy.
V1.0
Address
0x102C
0x1020
0x1024
0x1028
0x1030
0x1034
Address
0x1044
CE
CE
S
RATE
= sampling frequency (2520.6Hz), X = Pulse speed factor
=
PHADJ_A
PHADJ_B
CAL_VA
CAL_VB
CAL_IA
CAL_IB
WRATE
Name
WRATE
Name
⋅
WSUM
2
46
Default
⋅
16384
16384
16384
16384
F
S
0
0
Default
⋅
© 2005-2008 TERIDIAN Semiconductor Corporation
389
X
Hz
,
Description
These constants control the gain of their respective channels. The nominal
value for each parameter is 2
proportional to its CAL parameter. Thus, if the gain of a channel is 1% slow,
CAL should be scaled by 1/(1 – 0.01).
These two constants control the CT phase compensation. No compensation
occurs when PHADJ_X = 0. As PHADJ_X is increased, more compensation
(lag) is introduced. Range: ±2
angle Φ:
PHADJ
PHADJ
Description
Kh = VMAX*IMAX*47.1132 / (In_8*WRATE*N
value results in a Kh of 1.0Wh/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
CE Calibration Parameters
Pulse Generation
_
_
X
X
=
=
2
2
20
20
. 0
. 0
1241
1487
. 0
. 0
02229
−
0155
−
. 0
. 0
009695
14
15
0131
⋅
= 16384. The gain of each channel is directly
⋅
TAN
– 1. If it is desired to delay the current by the
TAN
⋅
Φ
⋅
TAN
15
TAN
Φ
– 1.
Energy Meter IC
Φ
Φ
at 60Hz
at 50Hz
ACC
*X) Wh/pulse. The default
71M6521BE
DATA SHEET
JANUARY 2008
Page: 81 of 97